Materials and Components - Engineering

Q1:

For a core having a relative permeability μr, magnetic dipole moment per unit volume M and field strength H, the flux density B is

A B = μr (H + M)

B B = μ0 (H + M)

C B = μ0μr (H + M)

D B = μ0μr (H - M)

ANS:B - B = μ0 (H + M)

How the answer is option B? Please explain.