Question

select the dependent clause. after a lightning bolt passes through the air, the compression and subsequent rapid expansion of the air molecules produces the booming sound of thunder.

Explanation:

A dependent clause cannot stand alone as a complete sentence and relies on an independent clause. "After a lightning bolt passes through the air" has a subordinating conjunction "after" and does not express a complete thought, so it is the dependent clause. The other part ("the compression... of thunder") is an independent clause as it can stand alone.

Answer:

After a lightning bolt passes through the air