The correct option is D All of the above
Electronic configuration of Fe is [Ar] 3d6 4s2 and that of Fe2+ is [Ar] 3d6 4s0.
According Pauli's exclusion principle, no two electrons can have all the four quantum number same. Hence, statement 3 is correct.
Only two electrons can exist in a orbital with opposite spin which limit maximum number of electrons to 2.
Vanadium has an atomic number of 23 hence it will have 23 electrons. So the spin quantum number can be either clockwise or anticlockwise. Therefore it will have 12 electrons of same spin (clockwise) and 11 electrons of other spin (anti-clockwise) or vice -versa.