Which choice best describes the underlined word or words in each sentence?

Question

The ancient Sumerians, Egyptians, and Chinese each developed a unique system of writing.

Underlined is:
Sumerians
Egyptians
Chinese

A- simple subject

B- compound subject

C- complete subject

D- none of the above

I think it is C.

Answer 1

Nope. Please think again.

Answer 2

B- compound subject.

Answer 3

Now you are right.

Answer 4

Thanks!!