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: If x and y are integers, what is the least positive number of 24x+18y?

 Option A: 3

 Option B: 6

 Option C: 9

 Option D: 12

 Option E: 15
[EX A]: Option B

[EX Q]: Question: There are some pigeons and hares in a zoo. If heads are counted, there are 120. If legs are counted, there are 580. The number of hares in the zoo is?

 Option A: 20

 Option B: 82

 Option C: 190

 Option D: 137

 Option E: 170
[EX A]: Option E

[EX Q]: Question: A boat goes 130 km downstream in 10 hours, and 75 Km upstream in 15 hours. The speed of the stream is?

 Option A: 3.5

 Option B: 3

 Option C: 5

 Option D: 4

 Option E: 8
[EX A]:
Option D