sugars do not function only in the production and storage of cellular energy. they also can be used to make mechanical supports. both plant and fungal cells gain structural support from cell walls composed of carbohydrate polymers. compare the chemical component(s) of these cell walls.

Both plant and fungal cells have a cell wall. The main difference between the fungal cell wall and the plant cell wall is that the plant cell wall is made up of cellulose whereas the cell wall of fungal cells are made up of chitin. Along with cellulose, the plant cell wall also comprises of hemicellulose and pectin.

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).