The correct answer is option 2: M~lLZT~2.

In physics, dimensions are used to represent physical quantities. Each dimension represents a fundamental characteristic of the quantity, such as mass, length, time, etc. The dimensions of a physical quantity can be derived by looking at its units.

The dimensional formula of the gravitational constant is given by:

[G] = M^1L^3T^-2

Breaking this down:

- M^1 represents the dimension of mass. This means that mass is raised to the power of 1.

- L^3 represents the dimension of length. This means that length is raised to the power of 3.

- T^-2 represents the dimension of time. This means that time is raised to the power of -2.

Therefore, the correct dimension of the gravitational constant is M~lLZT~2.

Alert - correct answer should be option 3: M2L~2T~2.