Three particles, each of mass m gram, are situated at the vertices of an equilateral triangle ABC of side f. cm (as shown in the figure). The moment of inertia of the system about a line AX perpendicular to AB and in the plane of ABC, in gram-cm2 units will be

• A. \[\frac{3}{2}m{{\ell }^{2}}\]
• B. \[\frac{3}{4}m{{\ell }^{2}}\]
• C. \[2m{{\ell }^{2}}\]
• D. \[\frac{5}{4}m{{\ell }^{2}}\]