I have no idea what it is help pls lol

I think rainfall

Explanation:

I believe it is rainfall since it is asking how are they directly replenished which means how are themselves being refilled and since it says underground, the ocean doesn't really go underground as much as rain does since rain can literally fall anywhere inland and then go into the ground unlike the rest of these options.

any abiotic or biotic factor in an ecosystem that causes a population's size to slow or decrease is a limiting factor.

nucleic acid molecules are incredibly complex, containing the code that guarantees the four different nucleotide units comprise dna, the nucleic acid of interest to the genealogist. and one of four nitrogen-containing molecules called nucleotides