Economics is the study of producing and goods and services.

Economics is the study of producing and consuming goods and services.

Economics show the GDP, or Growth domestic product, which show if a country is making more and intaking less products compared too others. The higher the GDP, usually (unless consumption is great too), the more built up the country is.

hope this helps

c

explanation:

i believe the answer is c and this is only worth 10 points you might wanna change it

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.