Homologous recombination occurs in all organisms but the nature of the events involved in homologous recombination between DNA molecules was first described in bacterial systems. Recombination is initiated by the RecBCD enzyme (also known as Exonuclease V), which has both nuclease and helicase activities. The enzyme complex is composed of three different subunits called RecB, RecC and RecD and hence the complex is named RecBCD. 

Here is some statement regarding RecBCD enzyme complex. 

P.  The RecB and RecD subunits each contain an ATP-dependent helicase.

Q. The RecC subunit recognizes a specific sequence in DNA, known as chi.

R. The RecD helicase travels on the strand with a 5' end at which the enzyme initiates unwinding, and RecB on the strand with a 3' end.

S. The RecB helicase travels on the strand with a 5' end at which the enzyme initiates unwinding, and RecD on the strand with a 3' end. 

T. The RecD subunit recognizes a specific sequence in DNA, known as chi.

Which one of the following statement is correct?