Wrong about nucleic acids

 Which is wrong about nucleic acids?

(a) DNA is single stranded in some viruses

(6lb) RNA is double stranded occasionally.

(c)Length of one helix is 45 A in B-DNA.

(d) One turn of Z-DNA has 12 bases.

In our books it's B DNA which has 10 base pairs but in options it's Z DNA which has 12 base pairs 

In some viruses its single stranded like 

 reverse transcriptase kia krta .ss RNS ko ss DNA me convert krta

So option C is wrong it's 34A