Which of the following molecules is inherited by living organisms?

One turn of the helix in a $B$-form $DNA$ is approximately (in $nm$)

$S$ Statement: $DNA$ is inherited by organisms produced by parents.
$R$ Reason: $DNA$ acts as a gene.
$(a)$ Both $S$ and $R$ are true,and $R$ is the correct explanation of $S$.
$(b)$ Both $S$ and $R$ are true,but $R$ is not the correct explanation of $S$.
$(c)$ $S$ is true and $R$ is false.
$(d)$ $S$ is false and $R$ is true.
$(e)$ Both $S$ and $R$ are false.

How many weak hydrogen bonds are present between $A$ (Adenine) and $T$ (Thymine)?

Which one of the following pairs of nitrogenous bases of nucleic acids is wrongly matched with the category mentioned against it?

What is the full form of $EtBr$?