I believe the answer would be d
Answer:
from what we see from the graph when the children had the 1st vaccine antibodies in the blood raised. then the concentration of the antibodies depleted, after the children had the second dose of the measles vaccine again, the antibodies in the children's blood raised drastically then the first dose.
Death, Burns and toxic gases.
Answer: Higher elevations allow you to see around the curve of the Earth’s horizon
explanation: knowledge