Final answer:
The archaic 3-letter word for a sphere or an eye is 'orb.' It is used historically and symbolically in art, such as representing the Earth or celestial bodies.
Step-by-step explanation:
An archaic 3-letter word for a sphere, or for the eye is orb. Both in historical contexts and in the symbolism of art, the word 'orb' has been used to refer to a spherical shape or a celestial body like the Earth or the stars. For example, in discussions about the celestial sphere, the concept of the sky as a vast dome resembling a spherical shape is similar to the earth being round as asserted by the Pythagoreans in ancient times. The word 'orb' also appears in the context of art history, referring to an object that symbolizes power or the earthly realm, such as in the depiction of angels wielding an orb. Therefore, the correct answer to this question is A) Orb.