Industrial communities should be close enough to crowded centers but enough to reduce ______. potential dangers.

A．DNA is characteristic of a region
B．they are beyond doubt of common ancestry
C．DNA strand has the ability to identify individuals
D．their unique identification can be provided via DNA

A．We are a walking, living, breathing record of our ancestors.
B．Many American slaves did not know who their ancestors were.
C．An adopted child generally lacks enough information to prove his identity.
D．Molecular genealogy can be used to prove a relationship between individuals.