The reason why haplotype blocks are still useful on current populations is because
a) some of our human ancestors interbred with neanderthals.
b) new mutations cannot be introduced into existing haplotype blocks.
c) they are still preserved in their original ancient configurations.
d) disease genes are found in haplotype blocks.
e) modern humans descended from a relatively small population of about 10,000 individuals that existed about two thousand generations ago.