Which of the sentences contain both an independent and a dependent clause? A. He was listening intently to the radio, and he didn't hear the doorbell.
B. As she entered the auditorium, she tripped over a backpack that had been carelessly left in the doorway.
C. Visiting the aquarium turned out to be quite an adventure; I enjoyed it thoroughly.
D. We understand the environmental concerns of the farming community, but we are aware that business owners have another point of view.

The correct answer is B:  As she entered the auditorium, she tripped over a backpack that had been carelessly left in the doorway.

Explanation:

An independent clause is a type of clause which contains both a subject and a predicate. This clause can stand alone in a sentence as it expresses a complete thought, and it can be joined to another dependent or independent clauses.

On the other hand, a dependant clause is a type of a clause that does not express a complete thought and it cannot stand alone in a sentence, although it contains a subject and a verb.

Option A contains two independent clauses, joined with the conjunction and:

1. He was listening intently to the radio and 2. He didn't hear the doorbell.

Option C also contains two independent clauses, separated with the semi-colon:

1. Visiting the aquarium turned out to be quite an adventure; and 2.  I enjoyed it thoroughly.

Option D contains two independent clauses, joined with the conjunction but:

1. We understand the environmental concerns of the farming community, but 2. we are aware that business owners have another point of view.

Option B contains one dependant and one independent clause:

Dependant clause. As she entered the auditorium, - This clause does not express a complete thought

Independent clause: she tripped over a backpack that had been carelessly left in the doorway.