What should be done if an unusual value is obtained in an experiment?

Correct answer: Record it and repeat the experiment

The direct answer is D: record the unusual value and repeat the experiment. An unusual result may be caused by a reading error, a faulty instrument, a mistake in procedure, an unusual sample, or a real scientific effect. The correct scientific response is not to remove data simply because it looks inconvenient. First record it honestly, then check the instrument, materials, units and method, and repeat the measurement or experiment when possible. Option D is correct because it protects the reliability and transparency of the investigation. Option A is wrong because immediate deletion hides evidence. Option B is wrong because replacing a real value with a “normal” value invents data. Option C is wrong because hiding it is dishonest and prevents others from checking the work. If repetition shows the same unusual result, it may be an important finding; if it disappears, an error may have occurred. Memory cue: unusual does not mean useless—record, check and repeat.