How do convection currents in the atmosphere form? A Warming air expands, becomes denser, and sinks. As the air sinks, it displaces cooler, less dense air which rises
B Warming air expands, becomes less dense, and rises. As the air rises, it pushes cooler, more dense air down
C Cooling air contracts, becomes denser, and sinks. As the air sinks, it displaces warmer, more dense air which rises
D Cooling air contracts, becomes less dense, and rises. As the air rises, it pushes warmer, more dense air down

B. Warming air expands, becomes less dense, and rises. As the air rises, it pushes cooler, more dense air down.

Explanation:

The options D and A can be eliminated because when a gas expands without gaining additional mass, it will become less dense; when a gas contracts without losing mass, it becomes more dense. Therefore, these two options conflict with the idea of density and cannot be true.

Option B is superior to Option C because convection currents are typically portrayed as beginning with the rise of warm air, which displaces/is replaced by cooler, dense air from the upper atmosphere. While Option C is similar, it describes the opposite series of events.

sheep is a herbivore animal whereas grasshopper belongs to the class chordates but both of them feed on greens.  

if grasshopper and sheep feeding on a pasture land, i do not think both of them will have any impact on each other. however, the number of the species can make difference. since sheep feed on greens, there is a possibility there left no pasture land for the grasshoppers or they may get extinct.

which