Answer : The option that uses a correct subordinate conjunction to join the sentences together is After I finish my homework, I go to the park.
Explanation:
A subordinating conjunction is a word or phrase used to link a dependent clauses to an independent one. This word usually indicates the relationship between both clauses: time, place, cause and effect, etc. Some of the most frequently used subordinating conjunctions are: after, although, as, because, since, unless, until, when, while. In this case, the conjunction used is after, the independent clause is I go to the park, and the dependent clause is After I finish my homework.