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.

[EX Q]: Problem: in what ratio must a grocer mix two varieties of pulses costing rs. 15 and rs. 20 per kg respectively so as to get a mixture worth rs. 16.50 per kg ?
Options: a. 3: 7, b. 5: 7, c. 7: 3, d. 7: 5, e. none
[EX A]: c

[EX Q]: Problem: a train 510 m long is running at a speed of 45 km / hr. in what time will it pass a bridge 140 m long ?
Options: a. 40, b. 52, c. 26, d. 21, e. 14
[EX A]: b

[EX Q]: Problem: julie put half of her savings in a savings account that pays an annual simple interest and half in a savings account that pays an annual compound interest. after two years she earned $ 120 and $ 122 from the simple interest account and the compound interest account respectively. if the interest rates for both accounts were the same, what was the amount of julie ' s initial savings ?
Options: a. 600, b. 720, c. 1080, d. 2200, e. 3600
[EX A]:
e