I need help with my homework and I don’t get complex sentences

The answer is D.

Explanation: Complex sentences include an independent clause and one or more dependent clauses.

An independent clause can stand alone: "The dog caught the ball."

The dog is the subject and caught is the verb.

Conversely, a dependent clause cannot standalone: "As it had drifted into the neighbor's yard."

This cannot standalone because the reader does not know what "It" refers to; therefore, this sentence depends on something else.

There are four types of sentences: simple sentence, compound sentence, complex sentence, and compound-complex sentence.

A simple sentence is, "The dog caught the ball."

A compound sentence is, "The dog caught the ball; it had drifted into the neighbor's yard.

In order to make this a compound-complex sentence (which is more than one independent clause, and one or more dependent clauses), you would select B.

"The dog caught the ball as it drifted into the neighbor's yard; he brought it back to me with his tail wagging."

This sentence is already a complex sentence because of one key word, "as." This is the word that hints to the reader that this is a dependent clause, and therefore it is a complex sentence.

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