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: if 9 / ( 1 + 4 / x ) = 1, then x =
Options: a. 3, b. 1 / 2, c. 1 / 3, d. - 1 / 3, e. - 3

A: b
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Q: Problem: an 80 - liter solution of cool - drink is made from 10 % jasmine water. if 5 liters of jasmine and 15 liters of water were added to the solution, what percent of the solution is jasmine ?
Options: a. 11 %, b. 13 %, c. 15 %, d. 17 %, e. 19 %

A: b
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Q: Problem: on the first of the year, james invested x dollars at proudstar bank in an account that yields 4 % in interest every quarter year. at the end of the year, during which he made no additional deposits or withdrawals, he had y dollars in the account. if james had invested the same amount in an account which pays interest on a yearly basis, what must the interest rate be for james to have y dollars at the end of the year ?
Options: a. 22.04 %, b. 26.12 %, c. 28 %, d. 16.25 %, e. 30 %

A:
d
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