$\textrm{Let assume that A & B are two students.}$
$\textrm{Now assume B’s marks are x & A’s marks are x+9}$
$\Rightarrow$ $A=(x+9) $
$\Rightarrow$ $B=x$
$\Rightarrow$ $\textrm{(x+9)=x+x+9(56%)}$
$\Rightarrow$ $25x+225=28x+126$
$\Rightarrow$ $3x=99$
$\Rightarrow$ $x=33$
$\textrm{So B=33,A=42}$
$\textrm{Option C}$