The correct answer is Complex
Explanation:
Complex sentences always contain at least two clauses: one dependent clause and one independent clause. Dependent clauses can be identified because they do not express a complete idea and therefore need from an independent clause. Besides this, in a complex sentence, it is common to find subordinating conjunctions such as before, because, although, unless, if, etc. that link the two types of clauses.
The sentence "Although I'll allow time off, the traffic is terrible" is a complex sentence because it contains a dependent clause "Although I'll allow time off" and one independent clause "the traffic is terrible". Moreover, the subordinating conjunction "although" shows the clauses do not have the same level of importance but one depends on the other to be complete.
