Which sentences below include only prepositional phrases (no participial or absolute phrases and no dependent clauses)? select all that apply

 There was no one visible ; under him, in the water, the dim shapes

of the swimmers had disappeared.

He could see nothing through the stinging salt water but the blank rock.

i think its:

c. a disadvantage of the proposal is that there will be fewer people under the monarchy.

the answer is c: at the city park,it has two basketball courts, a playground, and a walking path.