What is the semicolon doing in this sentence?

Emily loves milk, but she can’t drink it; she’s lactose-intolerant.

(1 point)
Responses

It’s separating items in a complex list.
It’s separating items in a complex list.

It’s uniting two closely connected clauses.
It’s uniting two closely connected clauses.

It's uniting two closely connected clauses.

The semicolon in this sentence is uniting two closely connected clauses. It separates the main clause "Emily loves milk" from the subordinate clause "she's lactose-intolerant," indicating a relationship between the two ideas.