Answer:Several theories have been proposed for the formation of desert pavements. A common theory suggests they form through the gradual removal of sand, dust and other fine-grained material by the wind and intermittent rain, leaving the larger fragments behind.
Explanation: scientists have had sever theories as stated in my answer above
I think the answer might be D
Answer:
Saving umbrella species helps in saving other species present in that ecosystem.
Explanation:
Umbrella species is the species which is important in an ecosystem because the presence and conservation of umbrella species helps in the conservation of other species present in the ecosystem. So the presence of umbrella species signifies that the ecosystem is healthy.
For example, the tiger is an umbrella species because the presence of a tiger helps in the thriving of other species like deer, monkeys, etc. Presence of tiger protects the habitat for many different species. Therefore scientists often focus their attention on saving umbrella species from extinction.
It is true that dead zones in waterways can occur as the result of fertilizer runoff.
