Renewable resources are valuable because

a. they are replaced naturally

b. they cannot be harmed by humans

c. they are humans’ main sources of energy

d. they cost little to use

A is definitely the best answer. Renewable resources are things like sunlight, wind, or tidal energy, which replace themselves without any human help.

B is wrong because renewable resources can definitely be harmed by humans. Sunlight can be blocked by pollution, for instance, and tides can be harmed by things like dams or erosion.

C is wrong because most of our energy comes from no renewable resources like fossil fuels (oil, coal, gasoline).

D is wrong because renewable resources can sometimes (but not all the time) be quite expensive to use. Hydroelectric energy requires extremely expensive dams, for instance, though wind power can sometimes be relatively inexpensive.

The answer is 1-plate movement along fault lines

Amath expression is a collection of one or more terms, which are separated by the signs ( + , - , x , / ).example :   8+b8+b  or  a−3a−3in algebra, an equation is a mathematical statement with two expressions where, each expression is separated by an equal (=) sign. variables can be present on both the sides of the equality (=) sign and we use letters to denote such variables.example 1:   x=4+2x=4+2  , [here, we can observe that the variable is present only on one side of the equation].example 2:   2x+3=x+42x+3=x+4  , [here, we can observe that the variables are present on both side of the equation].