The correct answers are:
A. People enjoy cruise vacations;
B. People need to cross the ocean;
E. People need to earn a living;
The vessels that are going through the ocean waters are both very useful and damaging in the same time, depending on the perspective. From one side, lot of people use them as a mean of traveling from one side to the other side of the ocean, millions of people enjoy going on vacation on the ocean/sea cruises, and also millions of people are employed and make a living from those vessels. On the other hand, all of the sewage from those millions of people is released into the ocean waters, thus causing pollution of the waters, which effects the marine life and its well-being.