C.
complete subject Is correct.
A compound sentence.
In a compound sentence, simple sentences become known as independent clauses; the two independent clauses together make up a compound sentence. ... The second is a simple sentence consisting of one independent clause with one subject and two verbs (or one verb used twice)
Example:
A man may die, nations may rise and fall, but an idea lives on.
I want to lose weight, yet I eat chocolate daily.
More examples here:
https://englishstudyhere.com/sentences/20-compound-sentences-in-english/
Answer:
I don't know for sure so I am sorry if its wrong.
Explanation:
The preposition is "on". The prepositional phrase is "had spent many hours working on". And it modifies the word "their"
Again I think I am wrong so I am so sorry.
Answer:
She receives a letter from Macbeth telling her about the witches prophecies. What is Lady Macbeth's main concern about her husband? He is too much of a wimp to kill King Duncan.
