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: of the 20 members of a kitchen crew, 17 can use the meat - cutting machine, 18 can use the bread - slicing machine, and 15 can use both machines. if one member is chosen at random, what is the probability that the member chosen will be someone who can not use either machine ?
Options: a. 0, b. 1 / 10, c. 1 / 7, d. 1 / 4, e. 1 / 3
[EX A]: a

[EX Q]: Problem: if a certain coin is flipped, the probability that the coin will land heads is 1 / 2. if the coin is flipped 6 times, what is the probability that it will land heads up on the first 4 flips but not on the last 2 flips ?
Options: a. 1 / 8, b. 1 / 16, c. 1 / 32, d. 1 / 64, e. 1 / 128
[EX A]: d

[EX Q]: Problem: jill has 14 gallons of water stored in quart, half - gallon, and one gallon jars. she has equal numbers of each size jar holding the liquid. what is the total number of water filled jars ?
Options: a. 3, b. 6, c. 9, d. 12, e. 24
[EX A]:
e