Answer:
Vaccination involves showing the immune system something which looks very similar to a particular virus or bacteria, which helps the immune system be stronger when it is fighting against the real infection.
Explanation: "it is what it is".
Centromere
Meaning the most condensed and constructed region
C.The density of ice is less than the density of water.
It would be Carbon Dioxide.
Water intake is essential in the prevention of heat related injuries