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.

Problem: if a mixture is 1 7 alcohol by volume and 2 7 water by volume, what is the ratio of the volume of alcohol to the volume of water in this mixture ?
Options: a. 4 / 2, b. 3 / 2, c. 1 / 2, d. 5 / 2, e. 7 / 2
c

Problem: a cyclist bikes x distance at 8 miles per hour and returns over the same path at 10 miles per hour. what is the cyclist ' s average rate for the round trip in miles per hour ?
Options: a. 8.1, b. 8.9, c. 8.6, d. 8.3, e. 9.0
b

Problem: find the value of ( 45 + 23 / 89 ) 89
Options: a. 4028, b. 4026, c. 4248, d. 4538, e. 9028
a