Which of the following steps in a signaling pathway typically occurs first once a chemical messenger reaches a target cell? Answer A: Specific genes are activated.

Answer B: A second messenger molecule is produced.

Answer C: A ligand binds to a receptor.

Answer D: Specific proteins are synthesized.

brain development. a child's brain undergoes an amazing period of development from birth to three—producing more than a million neural connections each second. the development of the brain is influenced by many factors, including a child's relationships, experiences and environment.

explanation:

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).