yes. but would they be overestimates or underestimates?
yesthen the trapezoid would be an under estimate
if we know that one has to be, then we could pick this one by process of elimination.and im not sure bout the midpoint
if you don't like that, my suggestion is to draw the rectangles for each rule on the same graph, so you can compare them side by side. to see which gives the largest area. of course, it helps to draw a grid over the figure so you can count the units of area. otherwise, come up with an example of a function that looks like this and actually do some estimates for it. use each of the rules to, say, find the area of the function $\displaystyle y = -x^2 + 5x$ between x = 0 and x = 5