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: Two pipes A&B can fill a tank in 24 min and 32 min respectively. If both the pipes are opened simultaneously, after how much time B should be closed so that the tank is full in 18 min.

 Option A: 8 min

 Option B: 3 min

 Option C: 21 min

 Option D: 23 min

 Option E: 24 min
[EX A]: Option A

[EX Q]: Question: Mr. Evans will states that each of his children will receive an equal share of his estate and that his grandchildren will split a portion of the estate that is equal to the share received by each of his children. If Mr. Evans has 4 children and 5 grandchildren, then approximately what percentage of Mr. Evans estate will each grandchild receive?

 Option A: 20%

 Option B: 17%

 Option C: 4.0%

 Option D: 3.3%

 Option E: 2.8%
[EX A]: Option C

[EX Q]: Question: In a certain province in Russia there are 15 cities. If a single road segment connects only two cities, how many road segments are required in order to connect the cities so that each city is connected to all other cities with a single road segment?

 Option A: 30

 Option B: 105

 Option C: 330

 Option D: 14!

 Option E: 15!
[EX A]:
Option B