In poetry, a group of three lines that often forms a stanza is known as a
a: cinquain
b: couplet
c: quatrain
d: tercet

D) Tercet.

Explanation: In poetry, a cinquain is a five-line stanza, a couplet is two lines of verse, usually in the same meter and joined by rhyme, that form a unit, a quatrain is a stanza of four lines, especially one having alternate rhymes, and finally, a tercet is a group of three lines that often forms a stanza, so, from the given options, the correct answer is the corresponding to option D: a tercet.

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."