Because they can only be seen with high density
The slope of 3x+6y=12 is y=2
Many Biomes have been effected by this but the main one would be the Tropical Rain forest,The Tropical Rain Forest depends on water the most out of all the Biomes.
Most people live near the Ganges River system, as the river provides water for irrigation for farming and is a major religious landmark.
The answer is A. in the Ganges River system.