A student is using a microscope to observe samples taken from pond water. She notices something that she thinks may be a living thing. Which feature would BEST support that the unknown sample is a living thing?

If the thing was moving- and it was manipulating the matter around it

Explanation:

Living things are characterized as living/not living through a couple of characteristics:

is it feeding itself? living things feed themselves from things in their surrounding enviroment.

is it growing? living things always grow/change. a rock doesn't grow and change.

does it reproduce? living things need to reproduce.

is it respirating?

is it moving?

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).