What is the structure of the sentence? The soup spilled on the floor but was easy to clean.

Question

A.
complex
 
 
 
B.
compound
 
 
 
C.
compound-complex
 
 
 
D.
simple

 

My guess is D.

Answer 1

this is an example of a compound sentence because there are two or more independent clauses joined by the coordinating conjunction "but"

Answer 2

Your guess is correct. A simple sentence can have a compound verb. See the link below, which defines the sentence types and gives examples:

http://eslbee.com/sentences.htm