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.

Example Input: Problem: the overall age of x and y is 19 year greater than the overall age of y and z. z is how many decades younger that x ?
Options: a. 11, b. 15, c. 12, d. 19, e. 20
Example Output: d

Example Input: 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
Example Output: d

Example Input: Problem: population of a city in 20004 was 1000000. if in 2005 there isan increment of 10 %, in 2006 there is a decrements of 35 % and in 2007 there is an increment of 45 %, then find the population of city atthe end of the year 2007
Options: a. 976374, b. 979923, c. 980241, d. 1036750, e. 1083875
Example Output:
d