Answer: until I turn sixteen in July
Explanation:
A dependent clause that starts with a subordinating conjunction such as "until" functions as an adverb. In this example, the adverb clause modifies the verb "drive" and starts with the subordinating conjunction "until". If the clause was located at the beginning of the sentence, it should be separated with a comma. In this case, since it´s at the end of the sentence, a comma is not required.
