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.
--------
Question: Problem: a train 510 m long is running at a speed of 45 km / hr. in what time will it pass a bridge 140 m long ?
Options: a. 40, b. 52, c. 26, d. 21, e. 14

Answer: b


Question: Problem: if x ^ 2 – 4 x = 5, then one possible value of x – 2 =
Options: a. - 9, b. - 5, c. - 3, d. - 1, e. 5

Answer: c


Question: Problem: if an average hard drive had a capacity of 0.4 tb in 2000, and average hard drive capacities double every 5 years, what will be the average hard drive capacity in 2050 ?
Options: a. 256, b. 512, c. 4096, d. 1024, e. 1536

Answer:
c