In which of the following places are you likely to find an area of high population density? North American Great Plains
South Asia
Andes mountains
Central Australia

So  if  the sum of the enthalpies of the reactants is greater than the products, the  reaction  will be  exothermic.  if  the products side has a larger enthalpy, the  reaction  is  endothermic. you may wonder why  endothermic reactions, which soak up energy or enthalpy from the environment, even happen

Iwould choose c or d

Ithink the best answer is d increased stability of all other biomes

No, because you are more likely to see volcanic mountains where magma is rising along the mid-ocean ridge spreading to the center.