According to Heisenberg’s uncertainty principle:

It is impossible to determine the exact position and exact momentum (i.e. velocity because of momentum= mass x velocity) simultaneously of an electron.

o One of its major implication is to rule out the existence of definite paths or trajectories of electrons, because a trajectory or a definite path of an object can be determined only if we know the exact location and the velocity of that object for a certain time being so that we can predict where it will be sometimes after that.

o But in case of sub-atomic particles like electrons, it is not possible to know both at the same time hence this principle had ruled out the idea of Bohr’s orbit or any possibility of a definite trajectory for electrons.

The other 3 options (i) Pauli’s exclusion principle, (iii) Hund’s rule of maximum multiplicity and (iv) Aufbau principle are not applicable in this case.