Answer:
C. the variable
Explanation:
(8x+9) -5 <----- The original question.
(8(1)+9) -5 <----- Replacing the variable.
(8 + 9) -5 <------ Completing the multiplication.
17 - 5 = <----- Doing the addition.
12
x = 1 tells us the "x" or the variable in this equation is a substitute for 1.