According to the passage, DNA fingerprinting can be unreliable when ______ .A．the methods

According to the passage, DNA fingerprinting can be unreliable when ______ .

A．the methods used of blood cell calculation are not accurate

B．two different individuals of the same ethnic group may have the same DNA fingerprinting pattern

C．a match is by chance left with fingerprints that happen to belong to two different individuals

D．two different individuals leave two DNA samples