What is the rhyme scheme of this stanza?

A small bird chirped outside

My window all day long.

I wondered if it knew

How much I loved its song.

AABCB
BABAC
CAABB
DABAB

Verified Answer :

A small bird chirped [outside] (A) 
My window all day [long.] (B)
I wondered if it [knew] (C)
How much I loved its [song] (B)

your answer is: A. ABCB
a. ABCB