Exponential growth is characterized by a quantity that increases by a constant percentage over equal time intervals. Let's analyze each option:
A. Shasta increases the amount she saves each month by 5%.
- This describes a linear increase, not exponential growth, because the amount she saves grows by a fixed percentage of her previous month's savings but does not compound monthly.
B. The population over the last decade of Black Rhino is such that it is nearing extinction.
- This does not describe exponential growth; instead, it indicates a population decline.
C. The amount of cell phone subscriptions in a small town increases by 75% each year.
- This is an example of exponential growth, as the increase is a constant percentage of the current total each year, leading to compounding growth.
D. The price of a stock goes up by 12% each year.
- This is also an example of exponential growth, as the price increases by a fixed percentage of its current value each year, resulting in compounding effects.
Based on this analysis, the options that represent exponential growth are C and D.