In an N- type semiconductor, there are :
A) Immobile positive ions.
B) Immobile negative ions.
C) Holes as majority carriers.
D) No minority carriers.

Hint
Although the Semiconductor is N – type semiconductor, it still carries minority charge carriers which are positive ions and in such a type of semiconductor they are immobile. Similarly in p- type semiconductor the minority charge carriers are negative ions which are immobile.

Complete step by step answer
When a pure semiconductor (Si or Ge) is doped with by a penta - valent impurity (P, As, Sb) then four electrons out of the five valence electrons take part in covalent bonding, with four silicon atoms surrounding it and the fifth electron is set free. These impurity atoms which donate free electrons for conduction are called Donor impurity (${N_D}$). Here free electrons increase very much so it is known as ''N'' type semiconductor. Here the impurity ions are known as ''Immobile Donor positive Ion''. Free electrons act as majority charge carriers and holes act as minority charge carriers.
Therefore, we can see that option (A) is correct.

Note
Whether it is a p-type semiconductor or an N- type semiconductor it does it matter, both are electrically neutral. Both have minority charge carriers and majority charge carriers which are holes and negative ions in case of p type semiconductor and vice versa for n type semiconductor.