In a chemotaxis experiment, cells are observed moving towards a higher concentration of a specific chemical. What does this indicate about the cells' behavior?

• A. The cells are indifferent to the chemical concentration.
• B. The cells are repelled by the chemical and are moving away from it.
• C. The cells are moving randomly without any direction.
• D. The cells are attracted to the chemical and are moving towards it.

Answer: (D)