Definition: Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.
Input: Problem: in the rectangular coordinate system, points ( 16, 0 ) and ( 16, 0 ) both lie on circle c. what is the maximum possible value of the radius of c ?
Options: a. 2, b. 4, c. 8, d. 16, e. none of the above
Output:
d