Answer:
A. Until she was seriously injured,
Explanation:
This is the option that uses the right punctuation. In this example, we are given a complex sentence. A complex sentence is a sentence that is composed of a dependent and an independent clause. A dependent clause is a clause that does not express a full thought and cannot exist on its own. When the dependent clause is placed before the independent clause, these have to be separated through the use of a comma.
