Final answer:
A heterotroph is an organism that relies on consuming other organisms for nutrition. The rattlesnake is a heterotroph, while the pine tree and grass are autotrophs.
Step-by-step explanation:
A heterotroph is an organism that cannot produce its own food and relies on consuming other organisms for nutrition. Out of the options given, only the rattlesnake is a heterotroph because it is a carnivorous reptile that obtains energy by consuming other animals. The pine tree and grass are both autotrophs as they can produce their own food through the process of photosynthesis.
Learn more about heterotrophs