Some pure black mice were mistakenly mixed with hybrid black mice. The quickest way to discover whether one individual black mouse is pure is

• A

  To cross it with pure black mouse and all the offsprings must be black

• B

  To cross it with a brown mouse and all the offsprings must be black

• C

  To cross it with a known hybrid black mouse and all the offsprings must be black or brown mice in equal numbers

• D

  To cross it with a pure brown mouse and all the offsprings must be black or brown in equal numbers