Answer:
i could be wrong but i think its
the rapid division of bacteria in the lymph nodes.
the rapid division of white blood cells in the lymph nodes.
One fourth means (one half) of (one half) .
So the 18 months must be two half-lifes.
The half-life of this particular isotope is 9 months.
D. Increase the amount of waste.
With a higher population, there will inevitably be a higher rate of pollution.