(C) The hand of a watch is the pointer which indicates the time and which one looks at when using the watch; the needle on a gauge (a car’s gasoline gauge, for instance) plays the same role. (The mercury in a thermometer is a little different; more than just a pointer, it is the substance which expands or contracts as temperature changes and therefore is the controlling mechanism of the entire device.)
Mercury: the eighth largest planet in the solar system and the one nearest to the sun: diameter, c. 4,880 km (c. 3,030 mi.); period of revolution, 88 earth days; period of rotation, 58.65 earth days; symbol.
Thermometer: an instrument for measuring temperatures, consisting of a graduated glass tube with a sealed.
Yardstick: a graduated stick or rod one yard in length, used in measuring
Gauge: a standard measure or scale Of measurement
Dial: the face of a watch or clock

(D) An explanation that is plausible is one that is possible or believable – it may or may not be true, but at least it doesn’t fly in the face of logic. Similarly, a theory that is defensible is one that knowledgeable people can advocate – it may or may not be true, but at least it makes basic sense
PLAUSIBLE: seemingly true, acceptable, etc.: often implying disbelief
Gullible: easily cheated or tricked; credulous Also
Deception: the act or practice of deceiving
Alibi: Law the defensive plea or fact that an accused person was elsewhere than at the scene of the crime with which the person is charged
Proposal: the act of proposing
Defensible: that can be defended, protected, or justified

(D) An actor is one member of a cast, which is the group of people who participate in a theater performance. In the same way, a musician is one member of an orchestra, the group which puts on a musical concert.
Protagonist: a person who plays a leading or active part
Sculptor: a person who models, carves, or otherwise fashions figures or forms of clay, stone, metal, wood, etc.; artist who creates three-dimensional representations
Script: a written document; original manuscript
Orchestra: in modern theaters, the space in front of and below the stage, where the musicians sit: in full orchestra pit
Composer: a person who composes, esp. one who composes music

(A) Something immaculate is very clean, completely without a stain; something colorless is completely without a hue.
IMMACULATE: perfectly clean; without a spot or stain; unsoiled
STAIN: to bring shame upon (someone‘s character, reputation, etc.); taint; disgrace; dishonor
Hue: city in central Vietnam, on the South China Sea; pop. 209,000
Eternal: without beginning or end; existing through all time; everlasting
Hermetic: completely sealed by fusion, soldering, etc. so as to keep air or gas from getting in or out
Formless: having no definite or regular form or plan; shapeless
Impervious: incapable of being passed through or penetrate

(D) The two words here have a time relationship: a harbinger comes before an event and helps to foretell or predict it (crocuses are harbingers of spring), while the aftermath is what follows an event and bears its traces. In the same way, a forebear is an ancestor, one who comes before a certain person or time; a descendant follows or comes after.
HARBINGER: a person or thing that comes before to announce or give an indication of what follows; herald
AFTERMATH: a result or consequence, esp. an unpleasant one
Precursor: a substance that precedes and is the source of another substance
Ancestor: any person from whom one is descended, esp. one earlier in a family line than a grandparent; forefather; forebear
Omen: a thing or happening supposed to foretell a future event, either good or evil; augury
Genesis: the way in which something comes to b; beginning; origin [G3] the first book of the Bible, giving an account of the Creation: abbrev
Descendant: a person who is an offspring, however remote, of a certain ancestor, family, group, etc.
Prediction: the thing predicted or foretold