Multiplication of Polynomials - Grade 8 (Question: 1612248465)

If the length and width of a rectangle are $(-3a^2 - 4a + 9)$ and $(-7a^2 - 5a -6)$, find the area of the rectangle.

A. $21a^4 + 43a^3 -25a^2 + 21a + 54$
B. $21a^4 + 43a^3 - 25a^2 - 21a - 54$
C. $21a^4 - 43a^3 - 25a^2 + 21a - 54$
D. $21a^4 + 43a^3 + 25a^2 + 21a + 54$