Why is insert integrity necessary in restriction digestion?

Correct answer: To preserve the function of the desired gene

Insert integrity means that the DNA fragment carrying the desired gene remains intact and retains its intended sequence and reading frame. Before choosing a restriction enzyme, the insert should be checked for internal recognition sites. If the enzyme also cuts within the insert, the gene may be split into pieces, its coding sequence may be disrupted, or important regulatory regions may be lost. The resulting construct might then fail to express the desired product even if ligation occurs successfully. Enzyme colour, water taste, and agar smell are irrelevant to genetic function. Therefore option A is correct.