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.

[EX Q]: Problem: a and b together can complete work in 6 days. a alone starts working and leaves it after working for 4 days completing only half of the work. in how many days it can be completed if the remaining job is undertaken by b ?
Options: a. 4, b. 12, c. 5, d. 6, e. 7
[EX A]: b

[EX Q]: Problem: car x began traveling at an average speed of 35 miles per hour. after 72 minutes, car y began traveling at an average speed of 49 miles per hour. when both cars had traveled the same distance, both cars stopped. how many miles did car x travel from the time car y began traveling until both cars stopped ?
Options: a. 105, b. 120, c. 140, d. 147, e. 168
[EX A]: a

[EX Q]: Problem: a basketball team composed of 12 players scored 100 points in a particular contest. if none of the individual players scored fewer than 7 points, what is the greatest number of points e that an individual player might have scored ?
Options: a. 7, b. 13, c. 16, d. 21, e. 23
[EX A]:
e