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: A seller of used cars has 18 cars to sell and each of his clients selected 3 cars that he liked most. If each car was selected exactly thrice, how many clients visited the garage?

 Option A: 8

 Option B: 10

 Option C: 12

 Option D: 18

 Option E: 16

A: Option D
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Q: Question: The cross-section of a cannel is a trapezium in shape. If the cannel is 16 m wide at the top and 4 m wide at the bottom and the area of cross-section is 700 sq m, the depth of cannel is?

 Option A: 76

 Option B: 28

 Option C: 27

 Option D: 80

 Option E: 70

A: Option E
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Q: Question: What is the next number of the following sequence
3,7,13,21,?

 Option A: 22

 Option B: 31

 Option C: 41

 Option D: 35

 Option E: 42

A:
Option B
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