Which statement describes an "either-or" decision?

A) Allen must decide how many courses to take this semester.
B) Sally must decide how many hours to spend studying for each of the four courses that she is taking this semester.
C) Chris must decide how many hours to work each week at his part-time job.
D) Dylan must decide whether to major in economics or finance.

An "either-or" decision presents a choice between two mutually exclusive options, such as majoring in economics or finance, as opposed to a decision that involves selecting from multiple options, such as how many courses to take or how many hours to work. Therefore, Dylan's decision to major in either economics or finance fits the definition of an "either-or" decision.