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: the average weight of a group of persons increased from 48 kg to 51 kg, when two persons weighing 78 kg and 93 kg join the group. find the initial number of members in the group ?
Options: a. 87, b. 67, c. 23, d. 75, e. 25

Answer: c

Question: Problem: if the average ( arithmetic mean ) of a and b is 45 and the average of b and c is 80, what is the value of c a ?
Options: a. 25, b. 60, c. 90, d. 140, e. it can not be determined from the information given.

Answer: b

Question: Problem: a company produces 50000 bottles of water everyday. if a case can hold 25 bottles of water. how many cases are required by the company to hold its one day production
Options: a. 2000, b. 4500, c. 5000, d. 8000, e. 9000

Answer:
a