Take a look at the sentence again:

Because his glasses were so thick, Quincy refused to get contacts, he worried that equally thick contact lenses would make him look like a bug-eyed space alien.

The problem occurs between contacts and he. Because his glasses were so thick, Quincy refused to get contacts is a complete sentence. He worried ... starts the next complete sentence. Because these two parts have just a comma between them, they create a comma splice, a major sentence error.

To fix the problem, you could put a period after contacts and then capitalize the H for he.

Go to the next sentence.

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