What is the difference between high concentration and low concentration

How much of the united states’ electric generation comes from coal? a. about 25% b. about 50% c. about 75% d. about 90%

Adesert is an example of a(n) and the gobi desert is an example of a(n) a. ecosystem biome b. biome ecosystem c. ecosystem climate d. climate biome

I’m his published 95 theses,martin luther protested against? a-the selling of indulgences within the catholic church b-the belief in predestination c-the worshipping of statues of saints d- the catholic church focus on faith as the sole means of salvation