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.

[Q]: Problem: set a contains all the even numbers between 2 and 50 inclusive. set b contains all the even numbers between 62 and 110 inclusive. what is the difference between the sum of elements of set b and the sum of the elements of set a ?
Options: a. 1500, b. 3100, c. 4400, d. 6200, e. 7400
[A]: a


[Q]: Problem: the average age of a family of 5 members is 20 years. if the age of the youngest member be 10 years then what was the average age of the family at the time of the birth of the youngest member ?
Options: a. 13.5, b. 14, c. 15, d. 12.5, e. none
[A]: d


[Q]: Problem: last year a worker saved 4 % of her annual salary. this year, she made 10 % more money than last year and she saved 5 % of her salary. the amount she saved this year was what percent of the amount she saved last year ?
Options: a. 137.5 %, b. 142.5 %, c. 147.5 %, d. 152.5 %, e. 157.5 %
[A]:
a