Final answer:
The correct coordination option is to use a semicolon (;) to join the two sentences.
Step-by-step explanation:
The correct coordination option that joins the two sentences is:
The professor is late for class; Liam has decided to major in biology.
The semicolon (;) is used to join two closely related sentences. In this case, the sentences express two separate actions without one depending on the other. Using a period would make them two separate sentences, while using a comma would create a comma splice. The semicolon maintains the independence of the statements while showing their relationship.
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