A chemical messenger that influences the behavior of other individuals is a(n):

• A. pheromone
• B. enzyme
• C. hormone
• D. neurotransmitter

Answer: (A)

Verified step by step guidance

1. Step 1: Begin by understanding the definition of each term provided in the options. A pheromone is a chemical substance released by an organism that influences the behavior or physiology of other individuals of the same species.
2. Step 2: Compare the definition of pheromone with the other options. An enzyme is a biological catalyst that speeds up chemical reactions but does not influence behavior directly. A hormone is a signaling molecule that regulates physiological processes within an organism, not between individuals. A neurotransmitter is a chemical messenger that transmits signals between neurons within an organism.
3. Step 3: Focus on the key aspect of the question: 'influences the behavior of other individuals.' This is a defining characteristic of pheromones, as they are specifically designed to affect other members of the same species.
4. Step 4: Eliminate the incorrect options based on their definitions and functions. Enzymes, hormones, and neurotransmitters act within an organism rather than influencing other individuals.
5. Step 5: Conclude that the correct answer is 'pheromone,' as it matches the description provided in the question and is distinct from the other options.