In a p-type semiconductor, the majority charge carriers are holes.

A p-type semiconductor is created by doping a pure semiconductor (such as silicon) with atoms that have fewer valence electrons than the host material. This creates a deficiency of electrons in the crystal lattice, resulting in positive charges. These positive charges are called holes.

Option 1, "free electrons," is incorrect because in a p-type semiconductor, there are relatively few free electrons available for conduction due to the presence of holes.

Option 2, "conduction electrons," is also incorrect because in a p-type semiconductor, conduction mainly occurs through the movement of holes rather than conduction electrons.

Option 3, "ions," is not the correct answer because although doping does introduce impurities into the semiconductor lattice, it does not result in the presence of ions as majority charge carriers.

Therefore, the correct answer is option 4, "holes." Holes are the positive charge carriers and play a significant role in the conduction of current in a p-type semiconductor.