Final answer:
The odds of two unrelated people having matching STRs at all 13 CODIS core loci are much lower than 1 in 1,000,000, typically estimated in the range of one in several billion, making option d) 1 in 1,000,000 a conservative approximation.
Step-by-step explanation:
The question refers to the probability that two individuals will have identical Short Tandem Repeats (STRs) across all 13 core loci used in the Combined DNA Index System (CODIS). The likelihood of two unrelated individuals sharing the same STR profiles at these loci is extremely low, given the high variability of these genetic markers in the human population. While the exact odds can vary depending on the populations being studied and the specific markers used, it is commonly accepted in forensics that the probability is significantly less than 1 in 1,000,000 for unrelated individuals to have completely matching STR profiles at all 13 CODIS core loci.
Therefore, the answer would generally be estimated in the range of one in several billion, which makes option d) 1 in 1,000,000 a conservative approximation, though still not fully representative of the incredibly low odds.