Choose the correct answer from the two choices you are given.
1. (Parallax, Spectroscopy) is used to determine how far away stars are.
2. Enzymes are (catalysts, organelles) that help cells make energy.
3. Mitochondria, lysosomes, and vacuoles are (organelles, proteins) inside cells.
4. (Ethologists, Anthropologists) are scientists who study animal behavior.