Question

repeat the experiment if ______ or if there was a measuring mistake. others are critical it takes less time than expected a step in the procedure was missed the topic is popular

Explanation:

To determine when to repeat an experiment, we analyze each option:

• "others are critical": Irrelevant to experimental procedure errors.
• "it takes less time than expected": Shorter time doesn't require repeating.
• "a step in the procedure was missed": Missing a step can invalidate results, so repeating is necessary (similar to a measuring mistake, which is also an error).
• "the topic is popular": Popularity doesn't relate to experimental validity.

Answer:

C. a step in the procedure was missed