H4? No. Move up to Row 5.
C5? No. F5? No. We don't need to move to Row 6 as clearly no shape can exist there. Therefore by process of elimination, we have discounted the possibility of figure 'A' being the answer. The advantage of this is even if you can't 'see' the other shape, at least you can make an 'educated guess' and improve your chances of getting a right answer.
Let's try figure 'E' now, just for the heck of it. I think in this case, I'll choose the vertex between the horizontal top line and the 45 sloping line. Why choose this feature in particular? Because there are many sloping lines which will confuse you, but not many horizontal lines. That's why we've chosen this characteristic, or feature of the shape if you like, to look at.
We start on Row 6 for obvious reasons. B6? No. D6? No. Down to Row 5.
E5? NO. Down to Row 4, row 3. Nope, no luck. Therefore figure E is out of the question.
Let's try Figure 'B'. The most obvios feature are the two parallel and sloping lines. Therefore, we look for this feature. It exists around the vicinity of A4 and B4, but the figure can't be extrapolated there. Therefore figure B is out of the question.
Let's have a look at figure 'C'. I think I will designate the vertical line on the left as the distinguishing feature as this is unique and you're not likely to get it confused with other lines. Column 'B'? No, none are long enough. D5-D3-C3? Possibly, this feature looks familiar. But then again it cant be extrapolated. Move on to column 'G'. G5-G3-F3? Nope can't be extrapolated. G6-G4-F4? Maybe. We see that it can indeed be traced out to match figure c- bingo! Now you've found it- Congratulations!
Although this process may seem drawn out and tedious, I assure you that by utilising this systematic method, you will have success in section 3. In fact if not for this method, I would have flunked it altogether.
Good luck! If you want me to explain any aspect of this reasoning then please don't hesitate to ask.