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: a solution of 70 litres contains oil and water in the ratio 9: x. if 6 litres of water is added to the solution, the ratio becomes 6: 4, find the value of x ?
Options: a. 6, b. 8.5, c. 9, d. 6.5, e. 5

Ex Output:
e


Ex Input:
Problem: a movie buff buys movies on dvd and on blu - ray in a ratio of 13: 4. if she returns 2 blu - ray movies, that ratio would change to 7: 2. if she buys movies on no other medium, what was the original number of movies purchased ?
Options: a. 22, b. 28, c. 77, d. 99, e. 119

Ex Output:
e


Ex Input:
Problem: gopi gives rs. 90 plus one turban as salary to his servant for one year. the servant leaves after 9 months and receives rs. 60 and the turban. find the price of the turban.
Options: a. 27, b. 30, c. 29, d. 10, e. 11

Ex Output:

b