Why is adaption most likely to a cactus survive and dry climate

In the context of the neural impulse, which of the following is true about the depolarization of neuron membranes?

Acceleration is a direct result of a.) balanced forces b.) unbalanced forces c.) gravity d.) velocity

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area