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.

Let me give you an example: Problem: a multiple choice test consists of 4 questions, and each question has 5 answer choices. in how many r ways can the test be completed if every question is unanswered ?
Options: a. 24, b. 120, c. 625, d. 720, e. 1024
The answer to this example can be: c
Here is why: 5 choices for each of the 4 questions, thus total r of 5 * 5 * 5 * 5 = 5 ^ 4 = 625 ways to answer all of them. Hence, the answer is c.

OK. solve this:
Problem: a ship 77 km from the shore, springs a leak which admits to 9 / 4 tonnes of water in 11 / 2 minutes. 92 tonnes of water would sink it. but the pumps can throw out 12 tonnes of water per hour. find the average rate of sailing so that the ship may just reach the shore as it begins to sink.
Options: a. 10.5, b. 11, c. 12, d. 13, e. 15
Answer:
a