NEED ANSWER ASAP!! Which is an example of an environmental concern within the study of resource economics?

A. how the extraction of ore affects the land
B. how regulation can be used to limit demand
C. how demand affects the supply of resources
D. how to farm greater numbers of freshwater fish

Astudent pours 10.0 g of salt into a container of water and observes the amount of time it takes for the salt to dissolve. she then repeats the process using the same amounts of salt and water but this time she slowly stirs the mixture while it is dissolving. the student performs the experiment one more time but this time she stirs the mixture rapidly. the dependent variable in this experiment is: time for salt to dissolve speed of stirring amount of water mass of salt