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: a can give b 100 meters start and c 200 meters start in a kilometer race. how much start can b give c in a kilometer race ?
Options: a. 111.12 m, b. 221.12 m, c. 271.12 m, d. 611.12 m, e. 191.12 m
[EX A]: a

[EX Q]: Problem: if an investor puts $ 700 in a savings account that earns 10 percent annual interest compounded semiannually, how much money will be in the account after one year ?
Options: a. $ 769.75, b. $ 771.75, c. $ 773.75, d. $ 775.75, e. $ 777.75
[EX A]: b

[EX Q]: Problem: two trains are running in opposite directions in the same speed. the length of each train is 120 meter. if they cross each other in 24 seconds, the speed of each train ( in km / hr ) is
Options: a. 18, b. 36, c. 28, d. 20, e. 24
[EX A]:
a