In a permanent magnet at room temperature.

Options

A. magnetic moment of each molecule is zero
B. the individual molecules have non-zero magnetic moment which are all perfectly aligned
C. domains are partially aligned
D. domains are all perfectly aligned

Explanation

AS we know a permanent magnet is a substance which at room temperature retain ferromagnetic property for a long period of time.
The individual atoms in a ferromagnetic material possess a dipole moment as in a paramagnetic material.
However, they interact with one another in such a way the they spontaneously align themseleves in a common direction over a macroscopic volume called domain. thus, we can say that in a permanent magnet at room temperature, domains are all perfectly aligned.