Final answer:
The sentence 'Sam played violin while his mom answered the phone' is a Complex sentence with one main clause and one subordinate clause. It is not a Simple, Compound, or Compound-Complex sentence.
Step-by-step explanation:
The sentence 'Sam played violin while his mom answered the phone' is best identified as a Complex sentence. This is because it contains one main clause ('Sam played violin') and one subordinate clause ('while his mom answered the phone'), which cannot stand alone as a sentence. The subordinate clause begins with the subordinating conjunction 'while', which indicates that the action is happening concurrently with the main clause action but does not form a separate, independent sentence.
To differentiate from other structures, a Simple sentence would have only one main clause, a Compound sentence would have two or more main clauses typically joined by a coordinating conjunction, and a Compound-Complex sentence would have at least two main clauses and one or more subordinate clauses.