Final answer:
The sentence that could best follow sentence 13 and provide additional support for the main idea of the third paragraph is: The city was probably an important entry port for trade into Egypt before it sank into the Mediterranean Sea so many centuries ago.
Step-by-step explanation:
The sentence that could best follow sentence 13 and provide additional support for the main idea of the third paragraph is: The city was probably an important entry port for trade into Egypt before it sank into the Mediterranean Sea so many centuries ago. This sentence strengthens the idea that the city was a major trading port by suggesting its significance as an entry point for trade into Egypt. The previous sentences mention the remains of ships, anchors, coins, and weights, all supporting the idea of a bustling trading port.
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