Given a math problem with context and a question and 5 answer choices, the task is to provide the correct answer choice based on the problem. You must choose one of the given answer choices by letter: a, b, c, d, or e; anything else is invalid.

Q: Problem: mr. loyd wants to fence his square shaped land of 120 sqft each side. if a pole is laid every 12 ft how many poles do he need ?
Options: a. 20, b. 30, c. 40, d. 50, e. 60

A: c
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Q: Problem: the sum of the ages of 5 children born at the intervals of 3 year each is 60 year. what is the age of the youngest child ?
Options: a. 4 year, b. 6 year, c. 10 year, d. none of these, e. 9 year

A: b
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Q: Problem: two trains, a and b, started simultaneously from opposite ends of a 120 - mile route and traveled toward each other on parallel tracks. train a, traveling at a constant rate, completed the 120 - mile trip in 6 hours; train b, traveling at a constant rate, completed the 120 - mile trip in 4 hours. how many miles had train a traveled when it met train b ?
Options: a. 28, b. 36, c. 48, d. 50, e. 54

A:
c
****