Mary is conducting an experiment on how pollution affects plant growth. How can she ensure that her data are reliable? by repeating trials during an experiment by keeping the results private by recording values without units by making a single observation

a) By repeating trials during an experiment

Explanation:

In science, repetition during experimentation is extremely important and fundamental. By repeting experiments, the researcher ensures that results are reliable and not due to a single factor or coincidence. If the same result is observed after several repetitions, then it could indicate that x factor is responsible for x result.

After this observation, the researcher will be able to analyze data statistically and discuss it in order for other scientists to repeat this methodology and explain a specific phenomenon accurately and thoroughly.