What's more natural?
(seeing a flower bouquet on the table)
A: Whose flowers are those? Who brought them?
OR
A: Whose flower bouquet is that? Who brought it?
B: It's from Jay.
A: Throw them away.
OR
A: Throw it away.

Plural or singular ?

Thank you.

Question

What's more natural?
(seeing a flower bouquet on the table)
A: Whose flowers are those? Who brought them? 
OR 
A: Whose flower bouquet is that? Who brought it?
B: It's from Jay. 
A: Throw them away. 
OR
A: Throw it away.

Plural or singular ?

Thank you.

Answer

A: They are both natural. "Whose flowers are those? Who brought them?" is the more casual of the two. You'll probably hear this the most.

B: Both are fine again. Your choice depends of course on what you chose to say in A.

Plural for flowers, singular for bouquet. Either is fine.

Answer

Both A questions are correct.
Answers: Use ‘them’ with flowers (plural). Use ‘it’ with bouquet (singular).