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: in a group of cows and chickens, the number of legs was 12 more than twice the number of heads. the number of cows was :
Options: a. 6, b. 7, c. 10, d. 12, e. 14
Example Output: a

Example Input: Problem: an industrial loom weaves 0.128 metres of cloth every second. approximately, how many seconds will it take for the loom to weave 25 metre of cloth ?
Options: a. 194 seconds, b. 195 seconds, c. 196 seconds, d. 197 seconds, e. none of these
Example Output: b

Example Input: Problem: the marks obtained by vijay and amith are in the ratio 4: 5 and those obtained by amith and abhishek in the ratio of 3: 4. the marks obtained by vijay and abhishek are in the ratio of ?
Options: a. 3: 4, b. 3: 5, c. 6: 5, d. 3: 6, e. 3: 8
Example Output:
b