What can a wrong band pattern in restriction digestion confirmation indicate?

Correct answer: Wrong insert or wrong clone

The direct answer is option A: a wrong band pattern can indicate a wrong insert or wrong clone. In restriction-digestion confirmation, the plasmid and its insert are cut with selected restriction enzymes. The resulting DNA fragments are separated by gel electrophoresis, producing bands. Before the experiment, the expected fragment sizes are predicted from the vector map and insert size. The observed pattern should reasonably match those predictions. If a band is missing, extra, or has an unexpected size, possible explanations include an incorrect insert, an incorrect clone, rearrangement, incomplete digestion, or another technical problem. Therefore option A is the best answer, although a wrong pattern does not prove only one specific cause. Option B is wrong because an unexpected pattern is not a perfect result. Option C is wrong because water alone does not normally create a meaningful plasmid band pattern; a failed control would more likely show no DNA signal. Option D is wrong because restriction confirmation examines DNA fragments, not merely a protein product. The correct practice is to compare the gel with the predicted map and include suitable controls. Memory cue: expected map plus observed bands; mismatch means investigate the clone or the digestion.