Bones, cartilage, and the ligaments that hold bones together muscular system

digestive system

skeletal system

Skeletal System

Explanation:

Skeletal system is the system that consists of bones, cartilage and the ligaments that hold bones together.

Hope this helped!

the answer is true when observing or determining population size, a direct observation is use, in which each organism is counted in a population or in an area. one benefit of this measure is that you get the exact population count but it will take a long time to  determine  the  size  of a  population.

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).