1. A rectangle has side lengths of 3x2 + 5x - 1 and -7x+1. Which of the following expressions represents the area of the rectangle?
a. 3x²-21
b. 3x² - 35x-1
c. -21x³ - 38x²- 2x - 1
d. -21x³ - 32x² + 12x - 1

please help​