The factor most likely to result in a decrease in the size of a specific population is

The factor most likely to result in a decrease in the size of a specific population is Famine.

Famine can causes shortage of water and food that can vanish a huge population from the earth.  

A famine can be a result of inflation, extreme weather, conditions and imbalance, war, and crop failure or government policies. A famine at a certain area can cause starvation, deprivation, high mortality rate and disease wide spread.  

what have scientists found to be the most efficient and effective way to insert new sequences into an individual? a-scientists have created genetically altered foods that release dna during digestion. b-scientists use viruses to insert specific gene sequences. c-scientists irradiate genes so that they can be absorbed through the skin.