If s(x) = x – 7 and t(x) = 4x2 – x 3, which expression is equivalent to (t circle s) (x)?
a. 4(x – 7)2 – x – 7 3
b. 4(x – 7)2 – (x – 7) 3
c. (4x2 – x 3) – 7
d. (4x2 – x 3)(x – 7).