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: water is leaking out from a cylinder container at the rate of 0.31 m ^ 3 per minute. after 10 minutes, the water level decreases 1 / 9 meters. what is value of the radius in meters ?
Options: a. 2, b. 3, c. 4, d. 6, e. 9

A: b
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Q: Problem: the cash realised on selling a 14 % stock is rs. 109.25, brokerage being 1 / 4 % is ?
Options: a. 366, b. 106, c. 102, d. 109, e. 122

A: d
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Q: Problem: sandy buys an old scooter for $ 900 and spends $ 300 on its repairs. if sandy sells the scooter for $ 1500, what is the gain percent ?
Options: a. 10 %, b. 15 %, c. 20 %, d. 25 %, e. 30 %

A:
d
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