Final answer:
Chiasmata cannot be used for mapping since they are not a specific DNA sequence but represent crossover points during meiosis. Microsatellites, SNPs, and RFLPs are valid markers for creating genetic maps.
Step-by-step explanation:
The DNA marker that cannot be used for mapping is chiasmata. Microsatellites, SNPs (single nucleotide polymorphisms), and RFLPs (restriction fragment length polymorphisms) are all used to create genetic maps. Microsatellites and SNPs are both variations that occur in the DNA sequence, while RFLPs involve variation in the length of restriction enzyme-digested DNA fragments. Chiasmata, on the other hand, refer to the points where chromosomes cross over during meiosis, which represent the physical locations of recombination events rather than a specific DNA sequence that can be used as a marker.