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.

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
c

Problem: the total age of a and b is 12 year more than the total age of b and c. c is how many years younger than a ?
Options: a. 12, b. 24, c. data inadequate, d. none of these, e. 34
a

Problem: last year a certain bond price with a face value of 5000 yielded 10 % of its face value in interest. if that interest was approx 6.5 of the bond ' s selling price approx what was the bond ' s selling price ?
Options: a. 7692, b. 5325, c. 5351, d. 6000, e. 6154

a