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.
--------
Question: Problem: a certain sum is invested at simple interest at 18 % p. a. for two years instead of investing at 12 % p. a. for the same time period. therefore the interest received is more by rs. 300. find the sum ?
Options: a. 7000, b. 2500, c. 2778, d. 2800, e. 2791

Answer: b


Question: Problem: how many prime numbers are between 29 / 3 and 87 / 6 ?
Options: a. 1, b. 2, c. 3, d. 4, e. 5

Answer: b


Question: Problem: 10 men and 15 women together can complete a work in 6 days. it takes 100 days for one man alone to complete the same work. how many days will be required for one woman alone to complete the same work ?
Options: a. 127 days, b. 667 days, c. 177 days, d. 187 days, e. 225 days

Answer:
e