The correct response is density dependence. Since the population growth rate is dependent on the size of the population, it is therefore regulated by density. This is the perfect example of a density dependent population. 

The correct response is density independence. The leafhopper population was not regulated by density. The only thing that regulated the population was abiotic events, such as forest fires. 

In terms of population trends, Nigeria can expect to see exponential growth in the following years for two reasons: Fertility rates are already quite high (e.g. a stable population is at  births per female) and a large portion of the population is under the age of fifteen. Present fertility rates ensure current exponential growth, while a large proportion of the population reaching reproductive age ensures future population growth, especially if the fertility rate remains inflated. 

Often, the growth of cities is too fast for the construction of adequate infrastructure. This results in transportation problems, including traffic gridlock and longer commuting times. The other answers are true regarding urbanization. Cities have a number of environmental drawbacks and benefits.

Ukraine, like many former Soviet Bloc countries, has a declining population due to political unrest. Nigeria, the Philippines, the United States and India all have increasing populations.

In the first stage of a demographic transition, a population has a high birthrate, a high death rate, and a stable population. Technological development is low, and populations are controlled mainly by famine and disease.

Replacement level fertility is the number of children required by a couple to replace them. Currently, in the United States, this number is just above two. This number accounts for infant mortality and varies by region.

The CITES treaty is the Convention on International Trade in Endangered Species of Wild Fauna and Flora, and entered into force in July 1975. The treaty's aim is to ensure that international trade in wild animals and plants does not threaten the survival of such endangered species, listed in varying degrees of protection and applying to more than 35,000 species. Thus it monitors international trade as it pertains to all manner of protected wildlife. 

The population growth rate is a measure of population change over a given time.

The first step to calculate this rate is to add up the number of people arriving in the country (through births and immigration) and, separately, add the number of people leaving the country (through death or emigration). Then we subtract those leaving the country from those entering the country to obtain a value for the change in population.  

After calculating the change in population, we can calculate the population growth rate.  Don’t forget to multiply the ratio between change in population and initial population by 100 to convert from decimal into percent. 

The correct response is GDP. All the other factors have major impacts on population growth. GDP has cultural implications for population growth; however, it is not a direct relationship.