C. testable and observable
<span>The answer is cysteine. This is a half essential proteinogenic amino acid with the formulation of HO₂CCHCH₂SH. It is prearranged by the codons UGU and UGC. The thiol side chain in cysteine frequently partakes in enzymatic responses, as a nucleophile.</span>
I think its because vaccines are just to help your body learn how to fight off the virus, it’s not to actually give you the virus. Hope this helped!
Antarctic fish. To stop their blood from freezing, some fish that live in the arctic and Antarctic have special Antifreeze proteins. Antifreeze proteins are very clever, as they slow down the formation of bonds between water molecules, which prevents the formation of ice crystals in the fish's blood.