Answer:
1. Until they were called home, the children played happily. (C)
Main clause: the children played happily
Subordinate clause: until they were called home
2. As we neared the hot-air balloon festival, the sky looked like a fairyland. (C)
Main clause: the sky looked like a fairyland
Subordinate clause: as we neared the hot air balloon
3. Although I didn’t brew it long, the coffee tastes bitter, and I will not drink it. (CC)
Main clause: the coffee tastes bitter
Main clause: I will not drink it
Subordinate clause: although I didn't brew it long
Step-by-step explanation:
A subordinate clause (or dependent clause) is a sentence that begins with a subordinate conjunction. Subordinate clauses are not full, independent sentences. Instead, as the name indicates, they are subordinate to another sentence, which is the main clause. Finally, a compound sentence is one that contains two or more independent clauses, while a complex sentence is one that combines an independent clause with a dependent or subordinate one.