The answer is C.
The sentence is a run-on as it shows 2 different subjects, the dog. and the cat.
Yes, it could've ended differently if the two families came to an understanding with each other. This would've changed the fact that Romeo and Juliet die, since you know, they were trying their best to get married secretly in fear that their families would continue fighting (maybe kill someone else).
A step you should make sure you revise in your essay of compare and contrast is making sure you have key words that states the differences and or similarities you are talking about.
1 point?? No ones gonna want to help
You did not provide possible answers, however, the story ideas that are usually found in gothic writing are darkness, madness, supernatural occurrences such as ghosts, dark castles, torture, brooding, decay, and similar. If any fit then that's your answer.