Final answer:
The best way to rewrite the sentences to make one complex sentence is option A: Debra waited at the airport for her best friend's arrival because it had been delayed for over 30 minutes.
Step-by-step explanation:
The best way to rewrite the sentences to make one complex sentence is option A: Debra waited at the airport for her best friend's arrival because it had been delayed for over 30 minutes. This option combines the two sentences into a single sentence using the subordinating conjunction 'because' to show the cause and effect relationship between the delay and Debra waiting at the airport.
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