The Figure Shows Two Point Sources of Light,A and B

The figure shows two point sources of light,A and B.B emits light waves that are +π radians out of phase with the waves from A.A is 3λ from P.B is 5λ from P.(λ is the wavelength. ) The phase difference between waves arriving at P from A and B is

A) 0 rad.
B) π rad.
C) 2π rad.
D) 3π rad.
E) 4π rad.