Nitrogen Stable Isotopes Are Useful Tools for the Study of Food

Multiple Choice

Nitrogen stable isotopes are useful tools for the study of food web structure because isotope ratios

A) change in predictable ways across trophic levels.
B) often vary among alternative food sources for a consumer.
C) for a predator exactly match the isotope ratio in its prey.
D) both change in predictable ways across trophic levels and often vary among alternative food sources for a consumer.