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.

[Q]: Problem: if a and b are the roots of the equation x 2 - 9 x + 9 = 0, then the value of a 2 + b 2 is :
Options: a. 63, b. 24, c. 17, d. 6, e. 5
[A]: a

[Q]: Problem: i flew my tiny seaplane to visit my mother. on the flight up, i flew at 96 mph. on the way home, i flew 88 mph. what was my average speed for the trip ?
Options: a. 198 mph, b. 110 mph, c. 92 mph, d. 100 mph, e. 99 mph
[A]: c

[Q]: Problem: if a tire rotates at 400 revolutions per minute when the car is traveling 48 km / h, what is the circumference of the tire ?
Options: a. 7 meters, b. 9 meters, c. 8 meters, d. 2 meters, e. 3 meters
[A]:
d