Answer: What this sentence needs to make it complete is an independent clause.
Explanation: "Although Toby mows the lawn" is a dependent clause<u>. A dependent clause has a subject and a verb, but it cannot stand alone as a sentence because it does not express a full thought</u>. In that way, a dependent clause needs an independent clause in order to be considered complete. Therefore,<u> "Although Toby mows the lawn" must be followed by an independent clause, such as "he does not enjoy doing it", in order to express a full idea. </u>