3 and 2. #20 is a little tricky. I would have picked 3 as the answer but then i looked closely and was able to tell the difference between the answer choice #3 and the top view. The line that vertically runs down the middle doesnt match with the top view.
In all the the drawings you should be able to match points the way I have. The perpendicular red lines are extension lines and for similar points they should all intersect at that 45* line.
In incorrect answers I have put blue circles indicating where two points should be the same in the different views but are not.
Its obvious why 1 and 4 are incorrect.
In 3, since the lower face in the top view is sliced horizontally, in the side view you wont see that side. The points in the blue circles confirm this seeing as they are associated with two completely different sets of lines.