The formula for the difference quotient is [f(x + h) - f(x)]/h, h ≠ 0. Use this formula to calculate the difference quotient of the following function:
f(x) = 3x² + 7x - 9

• A. 6x + 3h
• B. 6x + 3h + 7
• C. 2x + h
• D. 2x + 3h

Answer: (B)