81.
Land is considered a resource because it

82.
What is the source of energy for the water cycle?

84.
Which resource is both renewable and inexpensive?

85.
Sources of geothermal power are

87.
Which of the following is the second largest source of global energy?

88.
Which of the following is a renewable source of energy

89.
The energy that generates wind comes from what source?

90.
Solar energy is due to