Question

Which best describes the underlined words in the sentence? paula, harriet, and marshall went to the observatory to look at the stars.
a. complete subject
b. simple subject
c. compound subject

Answer 1

C) Compound subject. 
I'm assuming the underlined words are "Paula, Harriet and Marshall"
If not let me know
Hope this helps!

Answer 2

Answer is compound subject because there are more than one subject.