What natural resource does bolivia possess in abundance that hasn't been exploited? copper natural gas bauxite oil

Bolivia’s proven and probable volumes of gas were estimated at 76.4 billion cubic feet in 2006

Therefore I would suggest the answer to be B. Natural Gas

Natural Gas 
Bolivia has some of the largest natural gas reserves in the world.

Dall of the above all of the choices make sense

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].