Ans: A
$\begin{array}{cl}
& 4k-\dfrac{6+ki}{i} \\
= & 4k -\dfrac{(6+ki)i}{i^2}\\
= & 4k -\dfrac{6i-k}{-1} \\
= & 4k+6i
\end{array}$
$\begin{array}{cl}
& 4k-\dfrac{6+ki}{i} \\
= & 4k -\dfrac{(6+ki)i}{i^2}\\
= & 4k -\dfrac{6i-k}{-1} \\
= & 4k+6i
\end{array}$
