You are given a mathematical question described with a circumscribed mathematical vocabulary. Questions in this task usually contain some variables (e.g. X, Y), equations (e.g. X+Y=3) and some relationships (X is greater than Y). Often you need to find the value of the variable using equations and relationships. 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.

Example Input: When 28 is divided by 8, the remainder is the same as that obtained when 53 is divided by which of the following numbers?
(A)3 (B)4 (C)5 (D)6 (E)7
Example Output: E

Example Input: If \(100 - 2xy - y^2 = x^2\), which of the following must be true?
(A)\(x - y = 10\) (B)\(x^2 + y^2 = 100\) (C)\((x + y)(x - y) = 100\) (D)\((x + y)^2 = 100\) (E)\((x - y)^2 = 100\)
Example Output: D

Example Input: Let the function f be defined by \(f(t) = 6t\) for all numbers t. Which of the following is equivalent to \(f(t - r)\)?
(A)\(\frac{t - r}{6}\) (B)\(6t - r\) (C)\(6t - 6r\) (D)\(12(t - r)\) (E)36tr
Example Output:
C