To answer this question, we need to understand the meaning of the word "prodigious."
Option A) shell covering the back (of a turtle, tortoise, crab, etc.) - This option is incorrect because the definition provided does not match the meaning of the word "prodigious." "Prodigious" does not specifically refer to a shell covering the back of an animal.
Option B) border upon - This option is incorrect because the definition provided does not match the meaning of the word "prodigious." "Prodigious" does not mean to border upon something.
Option C) (of light or color) bright and distinct - This option is incorrect because the definition provided does not match the meaning of the word "prodigious." "Prodigious" does not specifically refer to the brightness or distinctness of light or color.
Option D) enormous - This option is correct because "prodigious" means enormous or very large in size, extent, or degree. It is often used to describe something that is extraordinary or impressive in size or amount.
The correct answer is D) enormous. This option is correct because it accurately represents the meaning of the word "prodigious."