Simplify the given expression.
(–3x2 – 9x + 17) – (15x2 + 20x – 4)

Question 1 options:
A. –18x^2 – 29x + 13
B. –18x^2 – 29x + 21
C. –18x^2 – 11x + 21
D. –18x^2 – 24x + 13