Apopulation of short-finned fish and a population of long-finned fish live in a lake. fish with long fins swim faster than fish with short fins, which means they escape predators more often. according to natural selection, which of the following will happen over time?

The trait small fins will disappear. This is, eventually,  there will be no more fish with small fins

Explanation:

Because long fins are being positively selected in nature (positive natural selection), the small fins will eventually (over time) disappear. That is, there will be no more fish with this characteristic, there will be no more fish with short fins.

The above is unavoidable unless there is a good trait (another)  linked to the small fins. If there is a good characteristic linked to small fins, that good trait will keep the short fins  in the population.

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.