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.

[Q]: Problem: what is the units digit of ( 3 ^ 13 ) ( 4 ^ 13 ) ?
Options: a. 2, b. 4, c. 6, d. 7, e. 8
[A]: a


[Q]: Problem: 1 men takes 37 $ to eat a pizza in restaurant such that it have discount multiple of 4 if u eat more pizza. discount increase by multiple of 4 every pizza u eat. for 1 pizza 0 % off. for 2 pizza % off for 3 pizza 8 % off. pizza without discount is 10 $. how much that man eats the pizza.
Options: a. 2, b. 3, c. 4, d. 5, e. 6
[A]: b


[Q]: Problem: in a certain pond, 50 fish were caught, tagged, and returned to the pond. a few days later, 50 fish were caught again, of which 5 were found to have been tagged. if the percent of tagged fish in the second catch approximates the percent of tagged fish in the pond, what is the approximate number of fish in the pond ?
Options: a. 400, b. 500, c. 1,250, d. 2,500, e. 10,000
[A]:
b