1.) dependent variable a.)the variable representing the
first elements of the ordered
2.) function pairs in a function; the inputs
b.)the variable representing the
3.) independent variable second elements of the
ordered pairs in a function;
the outputs
c.)a relation in which each first
coordinate is paired with
exactly one-second
coordinate

Explanation:

the answer is b

this is a good question! i'll do some research and come back when i have the answer!

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.