F is positive over the closed interval from zero to seven, and it is non-negative over seven to 12. I like this one as well. And actually, the reason why I would rule out this first one, this first one has nothing to do with the derivative, and so it's not a calculus-based justification, so I would rule that one out. This one is good. This is the exact rationale that I was talking about. F is positive from zero to seven, so it develops all this positive area, and it's non-negative over the interval, and so we are going to stay positive this entire time for g, which is the area under f and above the x-axis from zero to our whatever x we wanna pick. So I like this choice here.