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: the points a ( 0, 0 ), b ( 0, 4 a - 5 ) and c ( 2 a + 1, 2 a + 5 ) form a triangle. if angle abc = 90, what is the area of triangle abc ?
Options: a. 80, b. 82.5, c. 78.5, d. 75.5, e. 74
Output:
b