The correct answer is <u>B</u>: As she entered the auditorium, she tripped over a backpack that had been carelessly left in the doorway.
An <u>independent clause</u> 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 <u>dependant clause</u> 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.