Which of the following describes the findings in the early experiments looking at the relationships between birch and fir trees? the presence of birch trees is detrimental to the growth of trees both and birch are capable of sending carbon to eachother underground O fir trees shade the birch trees and prevent their growth birch trees outcompete fir trees for nutrients

the last one: artificial selection/genetic engineering

plant breeding is modifying the genetic composition of the plant - but this isn't cloning (which is specifically introducing a gene into a genome). but you are artificially selecting for the phenotype that you want.

the second one is literally genetic engineering - the gene would have been cloned first and then inserted or genetically engineered into the new plant cell (the cotton).