Which property of restriction enzymes is useful in DNA fingerprinting?

Correct answer: Cutting DNA at specific sites

Direct answer: Option A, cutting DNA at specific sites. A restriction enzyme first recognizes a particular short DNA sequence, called its recognition site, and then cuts the DNA at a defined position. Different DNA molecules have different arrangements of such sites, so digestion can produce fragments of different lengths. These fragments can be separated and compared during DNA fingerprinting; the resulting pattern helps distinguish DNA samples. Option A is correct because specific cutting creates a reproducible fragment pattern. Option B, making color in cells, is not the defining property and is unrelated to DNA fingerprinting. Option C, freezing water, is a physical change and has nothing to do with enzyme recognition. Option D, making proteins sweet, is not a biological function of restriction enzymes. Exam cue: specific sequence recognition plus cutting leads to DNA fragments and band patterns.