Explanation

(d) External force acting on the system is given as
$\mathbf{F}_{ext} = M\mathbf{a}_{CM}$
ie, $\mathbf{a}_{CM}$ lies in the direction of $\mathbf{F}_{ext}$.
Here, $\mathbf{F}_{ext} = 5\left( 2\widehat{\mathbf{i}} + 3\widehat{\mathbf{j}} - 5\widehat{\mathbf{k}} \right)$
$\mathbf{a}_{CM} = \text{2}\widehat{\text{i}}$+$\text{3}\widehat{\text{j}}$-$5\widehat{\mathbf{k}}$
Since, $\mathbf{F}_{ext}\ and\ \mathbf{a}_{CM}$ are not lying in the same direction, given data is incorrect.