Given the task definition and input, reply with output. 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: in a school with 5 classes, each class has 2 students less than the previous class. how many students are there in the largest class if the total number of students at school is 105 ?
Options: a. 24, b. 25, c. 26, d. 27, e. 28
b