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: A lady bought five books namely A,B,C,D,E to distribute her 7 friends. How many ways she can distribute books?

 Option A: 7^3

 Option B: 7^4

 Option C: 7^5

 Option D: 7^6

 Option E: 7^2
Option C

Question: The average age of 15 students of a class is 15 years. Out of these, the average age of 4 students is 14 years and that of the other 10 students is 16 years, The age of the 15th student is

 Option A: 11

 Option B: 12

 Option C: 9

 Option D: 14

 Option E: 15
Option C

Question: Numbers like 12345, 13542 and 21435 are some of the 120 different arrangements that can be made from the digits 1, 2 , 3, 4 and 5. If all 120 arrangements are placed in ascending manner, what will be the 87th number?

 Option A: 43255

 Option B: 53215

 Option C: 45215

 Option D: 43215

 Option E: 63215

Option D