Final answer:
The question does not provide enough context to determine how a species' teeth will evolve due to a population decrease. Changes in species' teeth would likely result from specific evolutionary pressures, not simply from a change in population size, and without information on these pressures, no prediction can be made.
Step-by-step explanation:
To test her hypothesis, a student can analyze the population using various methods, such as the mark and recapture method mentioned in one of the provided excerpts. When looking at population dynamics and the trends within it, if the population of a species is significantly decreasing and continues to do so, several outcomes are plausible depending on the pressures faced by that species.
However, the options provided in the question do not directly pertain to the population size decline, as changes to the species' teeth would more likely result from evolutionary pressures specifically related to their feeding mechanisms or prey hardness, rather than population size alone. Without additional context linking population decrease to changes in the species' teeth, none of the provided answers (sharper, smaller, stronger, larger) can be connected to the population decline with certainty.
Evolutionary changes, such as changes in the species' teeth, occur over many generations and are driven by natural selection, genetic drift, mutation, migration, and non-random mating. For instance, if a decreasing population size leads to a bottleneck effect, genetic variation can decrease, potentially affecting traits like tooth size or sharpness.
On the other hand, if the decrease in population is due to a change in available food resources or an increase in predators that require specific tooth adaptations for survival, then we might anticipate evolutionary pressure on teeth traits. Without specific information regarding what selective pressures are acting upon the teeth, we cannot determine how the teeth might change.