In which direction the magnetic field on the axis at a distance Z from the center of the bar magnet would be?
A. In the perpendicular direction of the magnetic moment $({\vec M})$ of the magnet.
B. In the direction of the magnetic dipole moment $({\vec M})$ of the magnet.
C. Its direction depends on the magnitude of the magnetic moment $({\vec M})$ of the magnet.
D. In the opposite direction of the magnetic dipole moment $({\vec M})$ of the magnet.

Hint: To answer this question we have to first understand magnetic moment and magnetic dipole moment and knowledge of bar magnet then we will be able to answer this type of question.

Complete step-by-step answer:
Now we have to understand magnetic moment:

Magnetic moment: A magnetic moment is a quantity that represents the magnetic strength and orientation of a magnet or any other object that produces a magnetic field.
orientation of a magnet or any other object that produces a magnetic field.

A magnet's magnetic moment is a quantity which determines the force the magnet can exert on electrical currents and the torque a magnetic field can exert on it. Both have magnetic moments: a pulse of electric current, a bar magnet, an electron, a molecule and a world.

Dipolar Magnetic Moment:

Moment of magnetic dipolarity. A vector quantity correlated with the magnetic properties of the loops or, more generally, magnets of electric current. This is equal to the sum of current flowing through the loop multiplied by the area covered by the loop, and its path is determined for rotations by the right hand law

Hence the magnetic field on the axis from the centre of the bar magnet would be in the direction of the magnetic dipole moment of the magnet.

Hence option B is the correct option.

Note: Whenever we get this type of question the key concept of solving is we have to understand all the terms used in the question and the option and then we will be only able to answer this type of question.