Answer:
The correct heading for a long essay about various activities to do at the beach is 'Parasailing, Hang-gliding, Snorkeling, and more!'
Explanation:
This is the perfect heading for an essay regarding activities to do at the beach since it names several activities that are typically done there.
'What to wear this summer' is not a possible option since this heading is possibly aimed at the summer 'trends/craze', that is to say, what people want to wear to fit in with the rest.
'Writing a Postcard' is not suitable because this is not normally done at the beach, it is rather done at home or the apartment. Plus, it only describes one acitvity, not various.
Finally, 'Choosing a Sunscreen' is not possible either because it also describes one single activity and one that is usually done at a shop or before going to the beach.
