Which of the following statements is true about the quadratic function f(x) = ax2 + bx + c?
Choose the correct statement below.
O A. The constants a, b, and c must be real numbers with a not ever equal to zero.
B. The constants a, b, and c must be real numbers with a always positive.
O C. The constants a, b, and c cannot ever be fractions.
D. The constant c determines whether the graph opens up or down.