The first restriction endonuclease type $II$,$...A..$,was isolated by Smith,Wilcox and Kelley from $...B...$ bacterium. It was found to cut $DNA$ molecules at a particular point by recognizing a specific sequence of six base pairs,known as the $...C....$. Here $A, B$ and $C$ can be:

• A
  $A-$Eco $RI, B-$Escherichia $RY 13, C-$Restriction sequence
• B
  $A-$Eco $RII, B-E. coli R 245, C-$Recognition sequence
• C
  $A-$Hind $II, B-$Haemophilus influenzae,$C$-Recognition sequence
• D
  $A-$Bam $HI, B-$Bacillus,$C-$Restriction sequence