C. By being honest in recording the results of their own experiments
Explanation:
Honesty in recording results is ethical behaviour and the basis of scientific research.
A. is wrong. If you repeat the same experiment, you should always get the same result.
B. is wrong. Copying someone else's results is cheating and certainly unethical behaviour.
D. is wrong. Making up data is dishonest and unethical behaviour.
E. is wrong. Following your own instincts about safety procedures is unethical because your instincts may be wrong. following them may result in injury to yourself or to others.
