Help me guys Suppose a cell has a defect in its P53 gene. The cell cannot respond to signals due to this defect. How could this lead to cancer? (Your answer should include what the signals are trying to say.)

"do a testcross with a homozygous recessive plant."

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).