What is the definition of a compound complex sentence

Question

A sentence with two or more main clauses and two or more subordinating clauses
A sentence with one main clause and one subordinating clause
A sentence with two or more main clauses
A sentence with one subordinate clause

Answer 1

The correct definition of a compound complex sentence is:

A sentence with two or more main clauses and one or more subordinating clauses.

So, it should include at least two independent clauses (main clauses) and at least one dependent clause (subordinating clause).