Question 11
A farmer has one mango tree that fruits well. Why graft from it rather than plant its seeds?
The right answer is the one marked above.
A graft is that tree and fruits sooner; a seed gives a mixture of it and whatever pollinated it. For a crop being sold, that certainty is usually worth more than the variety.
“A graft produces new varieties, which a seed cannot” is exactly backwards: new varieties come from seed, and "no new varieties arise" is the one disadvantage of vegetative propagation. So is a longer lifespan — a shorter lifespan is one of grafting's listed drawbacks, along with lower timber value and lower yield per season.