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: walking at 4 / 5 of her normal speed, a worker is 10 minutes later than usual in reaching her office. the usual time ( in minutes ) taken by her to cover the distance between her home and her office is
Options: a. 30, b. 35, c. 40, d. 45, e. 50

Answer: c


Question: Problem: find the sum of first 89 odd numbers
Options: a. 7921, b. 4800, c. 7900, d. 4980, e. 4960

Answer: a


Question: Problem: a towel, when bleached, was found to have lost 20 % of its length and 10 % of its breadth. the percentage of decrease in area is
Options: a. 28 %, b. 30 %, c. 32 %, d. 38 %, e. 40 %

Answer:
a