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: The ratio of a to b to c is 2 to 3 to 4, and a, b, c are positive integers. If the average (arithmetic mean) of the three numbers is 36, what is the value of a?

 Option A: 21

 Option B: 24

 Option C: 25

 Option D: 27

 Option E: 30
Option B

Question: What is the units digit of 18! + 5 ?

 Option A: 2

 Option B: 3

 Option C: 4

 Option D: 5

 Option E: 6
Option D

Question: In how many different ways can the letters of the word 'RUMOUR' be arranged?

 Option A: 180

 Option B: 90

 Option C: 30

 Option D: 720

 Option E: 60

Option A