<em>A natural disaster. </em>
Explanation:
A natural disaster would most likely have occurred to have the population of squirrels completely diverge from each other in order for them to become two separate species.
If a tornado, flood, earthquake, or another type of a natural disaster were to happen, it may have caused drastic damage to the ecosystem and environment of the squirrels. This would most likely cause the squirrels to split up, or diverge from each other and go to separate places in search of a new home.
Over time, these squirrels will reproduce with their own group. Each new group of squirrels, as they are both in different environments now, will have different adaptations from each other. This will eventually make it so they will never be able to reproduce with each other again if they were to meet, as they are now completely different species of squirrel.
It's the first one is the answer
The correct answer should be D. ecological footprint
Biodiversity means having various species living together while habitat is a place of residence of species. Sustainability refers to the question whether or not something is ecologically sustainable.
Through nerves attached to the brain and to the spinal cord. When an action potential traveling down the axon reaches a terminal button, they secrete a chemical called a neurotransmitter.
The brain communicates with the rest of the body through the spinal cord, which runs from the base of the brain all the way down the back. The spinal cord is made up of lots of nerves, and these nerves branch out into more nerves that travel to every part of the body.
<em>-</em><em> </em><em>BRAINLIEST</em><em> answerer</em>
