Let $a,b,c,d,e$ be the observations with mean m and standard deviations $S$. The standard deviation of the observations $a+k,b+k,c+k,d+k,e+k$ is

Question

$\begin{array}{1 1}(A)\; s \\(B)\;ks\\(C)\;s+k\\(D)\;s/k \end{array}$