Which of the following statements are true regarding functions? *Check all that apply

A. The horizontal line test may be used to determine whether a function is one-to-one.

B. A function is a relation in which each value of the input variable is paired with exactly one value of the output variable.

C. The vertical line test may be used to determine whether a function is one-to-one.

D. A sequence is a function whose domain is the set of real numbers.