What is true about the modeling equation that best fits the data?

Variable 1 Variable 2
20 351.70
45 252.95
35 389.95
5 20.95
25 396.95
40 337.70
15 273.95
30 409.70
50 135.70
10 163.70

a. The modeling equation does not have an extremum
b. The modeling equation has a point of inflection
c. The modeling equation is concave down
d. The modeling equation is concave up