Take another look at the sentence:

When Robert is riding his Honda motorcycle, he drives recklessly, weaving dangerously through rush hour traffic, Robert doesn't care that he might leave a kneecap or chunk of thigh speared on a car bumper.

No punctuation of any kind is necessary between care and that. Robert doesn't care is a main clause. That he might leave a kneecap ... begins a subordinate clause that must be attached to a main clause. Generally, when a subordinate clause follows a main clause, as in the example above, you need no punctuation between them.

Go back to the sentence to try again.

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