Question 5
How does a bulbil differ from a bulb?
The right answer is the one marked above.
A bulbil detaches from the plant to start a new one; a bulb stays where it is. An onion is a bulb — an underground stem. The air potato's small aerial tubers are bulbils.
“A bulbil grows underground; a bulb grows above ground” has it backwards: it is the bulb that is underground. Neither structure carries seeds, and both are asexual, so the answers about seeds and about sexual production are wrong on both counts.