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 overall age of x and y is 19 year greater than the overall age of y and z. z is how many decades younger that x ?
Options: a. 11, b. 15, c. 12, d. 19, e. 20
[EX A]: d

[EX Q]: Problem: a van takes 5 hours to cover a distance of 495 km. what speed in kph should the van maintain to cover the same distance in 3 / 2 of the previous time ?
Options: a. 60, b. 63, c. 66, d. 69, e. 72
[EX A]: c

[EX Q]: Problem: in the first 10 overs of a cricket game, the run rate was only 3.2. what should be the run rate in the remaining 50 overs to reach the target of 282 runs ?
Options: a. 6.25, b. 5.5, c. 7.4, d. 5, e. 6
[EX A]:
d