Three sequential nucleotides on mRNA are called a triplet.

A. elastic fibers:Elastic fibers are present in the skin, lungs, and blood vessel walls, providing resilience and the ability to stretch and recoil. In the skin, they maintain flexibility; in the lungs, they allow expansion and recoil during breathing; in blood vessels, they help accommodate pressure changes from blood flow.

B. reticular fibers:Reticular fibers form supportive networks in organs like the spleen, liver, and lymph nodes, but they are not a common feature of skin, lungs, or blood vessel walls.

C. simple squamous epithelium:Simple squamous epithelium is found lining blood vessels (endothelium) and alveoli in the lungs, but it is not present in the skin, so it is not a shared characteristic of all three tissues.

D. simple columnar epithelium:Simple columnar epithelium lines parts of the digestive tract and some glandular ducts but is absent from skin, lungs, and blood vessels, making it irrelevant as a shared feature.

A. transcription:Transcription is the process by which the DNA sequence of a gene is copied into messenger RNA (mRNA). This mRNA then exits the nucleus and carries the genetic code to ribosomes for protein synthesis.

B. replication:Replication is the process of copying the entire DNA molecule to produce two identical DNA strands during cell division. It does not produce mRNA and does not involve transporting genetic information out of the nucleus,