The city council is discussing whether or not to put fluoride in the city's water supply. many other towns add it already, but your town wants to research the topic before they make a decision. which would be the best group for them to ask for information on the topic? a. citizens from the town who are interested in the topic b. the company that supplies the fluoride c. the government agency responsible for monitoring water safety d. citizens from another town that currently add fluoride to their water

      D

Citizens from another town that currently add fluoride to their water

Explanation:

come closer and become far apart and become steam/gas

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.