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: the speed of a boat in still water is 15 km / hr and the rate of current is 3 km / hr. the distance travelled downstream in 24 minutes is
Options: a. 17.2 km, b. 7.2 km, c. 7.6 km, d. 17.6 km, e. 27.2 km
[EX A]: b

[EX Q]: Problem: the sum of all the integers a such that - 26 < a < 24 is
Options: a. 0, b. - 2, c. - 25, d. - 49, e. - 51
[EX A]: d

[EX Q]: Problem: a 120.00001 metres long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. what is the length of the other train ?
Options: a. 220 meter, b. 225 meter, c. 380 meter, d. 435 meter, e. none of these
[EX A]:
c