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.

[EX Q]: Question: A sequence contains y numbers of alternating positive and negative numbers, If the first number is postive and y is an even number, how many negative numbers are in it?

 Option A: (y+1

 Option B: (y-1

 Option C: y/(2+1

 Option D: y/(2-1

 Option E: y/2
[EX A]: Option E

[EX Q]: Question: A train passes a station platform in 36 sec and a man standing on the platform in 20 sec. If the speed of the train is 54 km/hr. What is the length of the platform?

 Option A: 229

 Option B: 240

 Option C: 288

 Option D: 277

 Option E: 221
[EX A]: Option B

[EX Q]: Question: Out of first 20 natural numbers, one number is selected at random. The probability that it is either an even number or a prime number is

 Option A: 1/2

 Option B: 16/19

 Option C: 4/5

 Option D: 17/20

 Option E: 3/5
[EX A]:
Option D