What is the subject in this simple sentence?

vertebrates are animals with a backbone or spine.

a.
animals

b.
spine

c.
backbone

d.
vertebrates

Which of the following are characteristics of free verse in “the child is not dead”? select all that apply. -sounds like spoken speech -use of punctuation at the end of each line -no regular rhyme scheme -use of rhymed words at the end of each line (edit) the answer is a & c