If you are talking about some specific like a type of schooner or a famous one that belonged to Queen Elizabeth, then it would be capitalized. So B is incorrect.
So is A. We need to change something.
D has the same problem as B. If you are talking about the Pacific Ocean, then Ocean would need a capital.
The answer is C. It is one of the fireworks that set off WWI. Lusitania must be capitalized. It is a specific ocean liner.