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: if the sum of 5 consecutive even positive integers is a, then the sum of the next 5 even consecutive integers in terms of a is :
Options: a. a + 5, b. a + 10, c. a + 25, d. a + 50, e. 2 a + 5
d

Problem: micheal and adam can do together a piece of work in 20 days. after they have worked together for 15 days micheal stops and adam completes the remaining work in 10 days. in how many days micheal complete the work separately.
Options: a. 40 days, b. 100 days, c. 120 days, d. 110 days, e. 90 days
a

Problem: for all even integers n, h ( n ) is defined to be the sum of the even integers between 2 and n, inclusive. what is the value of h ( 20 ) / h ( 10 ) ?
Options: a. 1.8, b. 60, c. 6, d. 18, e. 3

e