If a sentence has two subjects but only one verb, that means it

a. is a compound-complex sentence.

b. is a compound sentence.

c. has a compound subject, but it is not a compound sentence.

d. is a complex sentence.

The answer is option c.

If a sentence has two subjects but only one verb, that means it has a compound subject, but it is not a compound sentence.

for example: John and I went to the market.

In this sentence John and I are the compound subject, and went is the verb.