What is the first step when rewriting y = –4x2 + 2x – 7 in the form y = a(x – h)2 + k?

What is the first step when rewriting y = –4x2 + 2x – 7 in the form y = a(x – h)2 + k?

a. 2 must be factored from 2x – 7.
b. –4 must be factored from –4x2 + 2x.
c. x must be factored from –4x2 + 2x.
d. –4 must be factored from –4x2 – 7