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: the average of first six prime numbers greater than 20 is ?
Options: a. 10, b. 20, c. 30, d. 40, e. 34

Answer: e


Question: Problem: the cross - section of a cannel is a trapezium in shape. if the cannel is 12 m wide at the top and 2 m wide at the bottom and the area of cross - section is 4200 sq m, the depth of cannel is ?
Options: a. 500, b. 600, c. 700, d. 800, e. 900

Answer: b


Question: Problem: a boat running upstream takes 8 hours 48 minutes to cover a certain distance, while it take 4 hours to cover the same distance running downstream. what is the ratio between the speed of the boat and speed of the water current respectively ?
Options: a. 1: 3, b. 3: 8, c. 6: 3, d. 8: 3, e. none

Answer:
d