The correct answer is: A. moment of inertia
Moment of inertia is a measure of the resistance of an object to changes in its rotation. It is a property of an object’s mass and shape, and it is calculated using the following formula:
$I = mr^2$
where $I$ is the moment of inertia, $m$ is the mass of the object, and $r$ is the radius of the object’s rotation.
The dimensional formula for moment of inertia is $ML^2$. This can be seen from the formula above, where $m$ has the dimension of mass, $r$ has the dimension of length, and $I$ has the dimension of mass times length squared.
The other options are incorrect because they do not have the dimensional formula of $ML^2$.
- Option B, pressure, is a measure of the force exerted per unit area. It has the dimensional formula of $ML^{-1}T^{-2}$.
- Option C, elasticity, is a measure of the ability of a material to return to its original shape after being deformed. It does not have a specific dimensional formula, as it depends on the type of material and the type of deformation.
- Option D, couple acting on a body, is a pair of equal and opposite forces that act on a body at different points. It does not have a specific dimensional formula, as it depends on the magnitude of the forces and the distance between the points of application.