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: the mean of 50 observations is 200. but later he found that there is decrements of 34 from each observations. what is the the updated mean is ?
Options: a. 165, b. 166, c. 190, d. 198, e. 199
[A]: b

[Q]: Problem: the area of a square field is 625 km 2. how long will it take for a horse to run around at the speed of 25 km / h ?
Options: a. 12 h, b. 10 h, c. 8 h, d. 4 h, e. none of these
[A]: d

[Q]: Problem: a no. when divided by the sum of 555 and 445 gives 2 times their difference as quotient & 50 as remainder. find the no. is ?
Options: a. 145646, b. 236578, c. 645353, d. 456546, e. 220050
[A]:
e