Why B? And the second is a bit weird.
Yeah, exactly, I don't get the second at all, to be quite honest.
Ok, so I think it's B, because well major clue, is that heating is only occurring at A and B, so it has to be either one. When conducting a starch test, you must first boil the leaf in water to kill it (= liquid A is water) and then in alcohol, to dissolve the green chlorophyll so that the black coloring from when you put the iodine doesn't interfere and mix the colors up.
Another huge clue is the presence of the test tube, ethanol is a flammable liquid, so even if you have no idea about the starch test stages, you can just narrow it down to A and B, and guess with B since a test tube is present, so there's a higher chance that would be the answer.
Can anyone confirm this? And answer the second one?