Look at the graph. We can identify that f(x) = 2x + 3 is the dark green line and that g(x) = -x + 6 is the red line. We see that the two lines intersect when x = 0, so that's our answer!
H(t) = -16t^2 +42t = -16t(t -2.625) The maximum height will be reached at t=1.3125. It will be h(1.3125) = 16*1.3125^2 ≈ 27.6 Which corresponding to the 4th selection