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.

[EX Q]: Problem: if the sides of a triangle are 26 cm, 24 cm and 15 cm, what is its area ?
Options: a. 120, b. 772, c. 180, d. 266, e. 2848
[EX A]: c

[EX Q]: Problem: a / ( b / c. in the expression above, a, b, and c are different numbers and each is one of the numbers 2, 3, or 6. what is the largest possible value of the expression ?
Options: a. 2 / 18, b. 6 / 3, c. 30 / 2, d. 18 / 2, e. 6 / 18
[EX A]: d

[EX Q]: Problem: a cistern is filled by a tap in 6 1 / 2 hours. due to leak in the bottom of the cistern, it takes half an hour longer to fill the cistern. if the cistern is full how many hours will it take the leak to empty it ?
Options: a. 81, b. 85, c. 88, d. 91, e. 95
[EX A]:
d