If pathogens are present a tree is likely to have a. a disease
b. a healthy future
c. an insect infestation
d. overexposure to pesticides

a. a disease

Explanation:

Pathogens are disease-causing organisms. For example, some bacteria and viruses are pathogens for different species.

Therefore, a tree with pathogens present is likely to have a disease. Different pathogens affect different trees. Examples include Anthracnose , which is caused by a fungus

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).