Given the table of values for a continuous f(x) below, which of the following statements regarding the concavity of this function is TRUE?

x 3 4 5 6 7
f(x) 15 13 10 6 1

A. This function appears to be concave down on the entire interval
B. This function appears to be concave up on the entire interval
C. This function appears to be concave up between x=3 to x=5 and concave down from x=5 to x=7
D. This function appears to be concave down between x=3 to x=5 and concave up from x=5 to x=7