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: a couple who own an appliance store discover that if they advertise a sales discount of 10 % on every item in the store, at the end of one month the number of total items sold increases 15 %. their gross income from sales for one month increases by what percent ?
Options: a. 1.5 %, b. 2.5 %, c. 3.5 %, d. 4.5 %, e. 5.5 %
[A]: c

[Q]: Problem: a car is 15 minutes late by running at a speed of 4 / 5 th of its actual speed. the actual time taken by the car to cover that distance is :
Options: a. 30 minutes, b. 1 hour, c. 2 hours, d. 3 hours, e. none of these
[A]: b

[Q]: Problem: 102 a 102 + 98 a 98 = ?
Options: a. 20018, b. 20028, c. 20108, d. 10008, e. 20008
[A]:
e