Which of the following verbal expression represents the algebraic expression 2x-8?

The verbal expression that represents the algebraic expression 2x-8 is "twice a number decreased by 8." In this expression, "2x" represents twice the value of a variable "x," and "-8" indicates that 8 is being subtracted from that value. Therefore, "twice a number decreased by 8" accurately describes the algebraic expression 2x-8.