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.

[Q]: Question: A contractor undertakes to built a walls in 50 days. He employs 60 peoples for the same. However after 25 days he finds that only 40% of the work is complete. How many more man need to be employed to complete the work in time?

 Option A: 25

 Option B: 90

 Option C: 35

 Option D: 20

 Option E: None of these
[A]: Option B


[Q]: Question: Factor (x + 4)3 - 9x - 36 =

 Option A: (x - 4

 Option B: (x + 6

 Option C: (x + 4

 Option D: (x + 4

 Option E: None
[A]: Option D


[Q]: Question: What is the greatest prime factor of 4^18 - 2^28?

 Option A: 2

 Option B: 3

 Option C: 5

 Option D: 7

 Option E: 127
[A]:
Option E