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: Which of the following is NOT a factor of 10! ?

 Option A: 1440

 Option B: 625

 Option C: 160

 Option D: 80

 Option E: 50
[A]: Option B


[Q]: Question: Find the equation of a line which passes through A(4, -1) and is parallel to x axis.

 Option A: y=-2

 Option B: y=3

 Option C: y=2

 Option D: y=-1

 Option E: y=0
[A]: Option D


[Q]: Question: Find the ones digit of 73^300

 Option A: 3

 Option B: 5

 Option C: 6

 Option D: 7

 Option E: 10
[A]:
Option E