Cedric completed the square for the quadratic expression 5x2−40x+15 in order to determine the minimum value of the expression, as shown. Step 1: 5(x2−8x+3)
Step 2: 5(x2−8x+16−16+3)
Step 3: 5((x+4)2−16+3)
Step 4: 5((x+4)2−13)
Step 5: 5(x+4)2−65
What mistake, if any, did Cedric make?

a. He did not make a mistake.
b. In Step 1, he incorrectly factored out 5. He should have written 5(x2−8x−3).
c. In Step 5, he incorrectly distributed 5 from the parentheses. He should have written 5(x+4)2−13.
c. In Step 3, he incorrectly wrote the square as (x+4)2. He should have written x−42.
d. In Step 2, he incorrectly added 16 and −16. He should have written 5(x2−8x+64−64+3).