Correct Option: D

Gene therapy is the therapeutic delivery of nucleic acid polymers into a patient’s cells as a drug to treat disease. Avidin is a protein derived from both avians and amphibians that shows considerable affinity for biotin, a co-factor that plays a role in multiple eukaryotic biological processes. only be used to obtain a viability count, not a total cell count (cells/mL).  The viability will be determined by the trypan blue assay , and it can be used with the total cell count (obtained from a Coulter counter) to determine a total count of viable cells, as : Number of viable cells = (% viability)*(Total number of cells) ​​