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 Input:
Problem: the speed of a boat in still water is 15 km / hr and the rate of current is 3 km / hr. the distance travelled downstream in 24 minutes is
Options: a. 17.2 km, b. 7.2 km, c. 7.6 km, d. 17.6 km, e. 27.2 km

Ex Output:
b


Ex Input:
Problem: a textile manufacturing firm employees 100 looms. it makes fabrics for a branded company. the aggregate sales value of the output of the 100 looms is rs 5, 00,000 and the monthly manufacturing expenses is rs 1, 50,000. assume that each loom contributes equally to the sales and manufacturing expenses are evenly spread over the number of looms. monthly establishment charges are rs 75000. if one loom breaks down and remains idle for one month, the decrease in profit is :
Options: a. 13000, b. 7000, c. 10000, d. 3500, e. none of these

Ex Output:
d


Ex Input:
Problem: two bullet train s 140 m and 180 m long run at the speed of 60 km / hr and 40 km / hr respectively in opposite directions on parallel tracks. the time ( in seconds ) which they take to cross each other, is :
Options: a. 15.8 sec., b. 11.52 sec., c. 11.8 sec., d. 10.8 sec., e. 08.8 sec.

Ex Output:

b