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

Multiple Choice

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.