Answer: Compound sentence.
Explanation: Compound sentences contain 2 independent clauses combined by a comma and coordinating conjuction.
[Mom baked cookies for the school picnic] - Independent clause
[Dad volunteered to grill the hamburgers] - Independent clause
Both the sentences are independent clauses and are combined by the coordinating conjuction ( and) and a comma.
1. an air of melancholy surrounded him
2. an air of melancholy surrounded him
3. the decree guaranteed freedom of assembly
4. Rose's parents emigrated to Australia
5. the patriots had to capitulate to the enemy forces
7. all ivory trafficking between nations is prohibited
8. they offer sacrifices to the spirits
I'm probably going to Montana next summer, i believe would be the best answer because its the only choice that really makes sense when you say it out loud.