I think the correct answer from the choices listed above is option B. Alleles that are both expressed in the phenotype when they are together are called codominance. Alleles are masked or hidden by dominant alleles. Hope this answers the question. Have a nice day.
After the macrophage fails the Helper T Cell stimulates the B cells if pathogen is extracellular and Cytotoxic T Cells if the pathogen is intracellular. Once the pathogen is killed the B Cells create Memory B Cells and the Killer T Cells create memory T Cells.
