He is the portion of the earth that supports living things.

Which of the following is a measure of the amount of light a star directly emits? a. luminosity b. wavelength c. brightness d. intensity

Which barrier to economic development is shown in the following examples? i. the high rate of hiv infection in underdeveloped nations ii. the use of children as soldiers in uganda’s army in the early 2000s iii. low literacy rates in underdeveloped nations with limited exposure to adequate education a. foreign debt b. political instability c. widespread disease d. low levels of social welfare

Describe the four major spheres of the earth system; identify the parts of the earth they each represent. explain what is meant by the "earth system."