You are given a mathematical question described with an open-ended vocabulary. Questions in this task involve real-world situations, describing a mathematical problem. You are also given 4 or 5 answer options (associated with "A", "B", "C", "D", "E"). Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D', 'E'. LaTeX mathematical format (the standard way to express mathematical expressions in the typesetting software known as LaTeX) is used to express equations. Each question is solvable with high school math knowledge. Give only one answer for each question.

[EX Q]: A line of plastic ducks moves across a conveyor belt at a shooting gallery. The color of each duck follows the repeating pattern orange, green, red, blue, yellow, purple, continuing indefinitely. If the first duck is orange, what is the color of the 50th duck?
(A)Green (B)Red (C)Blue (D)Yellow (E)Purple
[EX A]: A

[EX Q]: There are a total of 20 marbles in a bag containing only red marbles, blue marbles, and yellow marbles. If a marble is selected at random, the probability of getting a red marble is \(\frac{2}{5}\) and the probability of getting a blue marble is \(\frac{1}{2}\). How many yellow marbles are in the bag?
(A)1 (B)2 (C)4 (D)8 (E)10
[EX A]: B

[EX Q]: The probability of choosing a black marble from a jar containing only black and red marbles is \(\frac { 1 } { 4 } \). Which of the following could be the number of red marbles?
(A)20 (B)22 (C)24 (D)32 (E)35
[EX A]:
C

