Waves from Two Slits Are in Phase at the Slits

Multiple Choice

Waves from two slits are in phase at the slits and travel to a distant screen to produce the third side maximum of the interference pattern. The difference in the distance traveled by the waves is:

A) half a wavelength
B) a wavelength
C) three halves of a wavelength
D) two wavelengths
E) five halves of a wavelength