Saul's muscle cells are said to have built up an oxygen debt. What must Saul do in order to 'repay' this debt?

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).

answerpotassium hydroxide preparation;

treatment of fungal infections usually follows diagnosis confirmed by potassium hydroxide preparation or culture;