You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.

Question: Find the average of all the numbers between 11 and 36 which are divisible by 5

 Option A: 15

 Option B: 20

 Option C: 25

 Option D: 30

 Option E: 35
Option C

Question: If j and k are integers whose product is 400, which of the following statements must be true?

 Option A: n + k > 0

 Option B: n is not equal to k.

 Option C: Either n or k is a multiple of 10.

 Option D: If n is even, then k is odd.

 Option E: If j is odd, then k is even.
Option E

Question: A bookshop had science and art books in the ratio of 2:5. By the end of the week, 20% of both type of books were sold and 2240 books were unsold. How many art books were there at the starting?

 Option A: 1355

 Option B: 1350

 Option C: 1450

 Option D: 1600

 Option E: 2000

Option E