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: if the price of a certain computer increased 30 percent from b dollars to 351 dollars, then 2 b =
Options: a. 540, b. 570, c. 619, d. 649, e. 700
[EX A]: a

[EX Q]: Problem: if a randomly selected positive single digit multiple of 3 is multiplied by a randomly selected prime number less than 20, what is the probability w that this product will be a multiple of 45 ?
Options: a. 1 / 32, b. 1 / 28, c. 1 / 24, d. 1 / 16, e. 1 / 14
[EX A]: c

[EX Q]: Problem: a train 140 m long is running at 60 kmph. in how much time wiu it pass a platform 260 m long ?
Options: a. 21 sec, b. 22 sec, c. 23 sec, d. 24 sec, e. 26 sec
[EX A]:
d