What do short tandem repeats (STRs) indicate in DNA profiling?

Short tandem repeats (STRs) are a type of repetitive DNA sequence in which a short sequence of nucleotides is repeated multiple times in a row. These repeats are found in non-coding regions of DNA and vary significantly between individuals, making them particularly useful as genetic markers in DNA profiling.

The correct answer highlights that STRs serve as unique genetic markers for individuals. Each person has a different number of repeats at specific STR loci, which can be analyzed to create a DNA profile. This variability allows for the differentiation between individuals, making STRs valuable for applications such as forensic science, paternity testing, and genetic diversity studies.

In contrast, options that suggest STRs indicate variations in coding genes, stable genetic information, or identical sequences among individuals do not accurately capture the role and characteristics of STRs in DNA profiling. STRs do not typically relate to coding genes, as they are primarily situated in non-coding regions, and their variability does not suggest stability across individuals. Identical sequences would negate the uniqueness that STRs provide, which is the fundamental basis for distinguishing between genetic profiles.