If you fill in x=0, you are left with the y intercept. In the picture you can see it must be larger than y=10. This invalidates answer A and D.
The x-coordinate top of the parabola ax²+bx+c=0 is given by y = -b/2a, so immediately we can see -b has to be positive. This leads you to answer C because -9x implies b=-9, and --9 is positive.
