Our experiment was to keep one seedling set in a light place and the other set in a closed cardboard box. So my question is to explain why it is important to keep one set of seedlings in the light. I hope to get a perfect answer

To examine the importance of light to a plant's growth.

Explanation:

To give a background to this question, I will define a key term "Photosynthesis". Photosynthesis is a compound word made up of photo (which means "light") and synthesis (which means "to put together").

It is the process by green plants use sunlight to obtain nutrients from carbon dioxide and water.

The experiment us meant to examine the effect of deprivation of sunlight on a plant's growth.

Therefore, the essence of keeping one set of seedlings in the light is to compare if there is any difference in growth between the seeding kept in the dark cupboard and that kept in the light.

This enables us to conclude whether or not light is important for the growth of a plant.

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).