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 group of boy scouts and girls scouts is going on a rafting trip. 45% of the scouts arrived with signed permission slips. If 60% of the scouts were boy scouts and 25% of the boy scouts arrived with signed permission slips, then what percentage of the scouts were girl scouts who arrived with signed permission slips?

Option A: 20

Option B: 21

Option C: 25

Option D: 28

Option E: 30
[EX A]: Option E

[EX Q]: Question: How many odd 4-digit positive integers R that are multiples of 5 can be formed without using the digit 3?

Option A: 648

Option B: 729

Option C: 900

Option D: 1296

Option E: 3240
[EX A]: Option A

[EX Q]: Question: A train 540 meters long is running with a speed of 54 kmph. The time taken by it to cross a tunnel 180 meters long is?

Option A: 33

Option B: 77

Option C: 48

Option D: 99

Option E: 22
[EX A]:
Option C