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: if the simple interest on a certain sum of money for 6 years is one – fifth of the sum, then the rate of interest per annum is
Options: a. 3.3 %, b. 7.2 %, c. 6.1 %, d. 5.0 %, e. 3.1 %
Example Output: a

Example Input: Problem: the size of a television screen is given as the length of the screen ' s diagonal. if the screens were flat, then the area of a square 19 - inch screen would be how many square inches greater than the area of a square 17 - inch screen ?
Options: a. 36, b. 4, c. 16, d. 38, e. 40
Example Output: a

Example Input: Problem: a merchandise feedback online portal accords ‘ ratings ’ to a product by recording the percentage of customers who have reported their views as either ‘ satisfied ’ or ‘ unsatisfied ’ only. the portal rounds off the exact percentage value calculated to the closest integral value. if the percentage of unsatisfied customers as recorded by the portal is 57 %, what is the least possible number of people that could have reported their views as ‘ satisfied ’ ?
Options: a. 2, b. 3, c. 12, d. 43, e. 57
Example Output:
b