Answer
See below.
Work Step by Step
Light behaves as a wave while in transit through lens, and where they strike the screen (i.e., the resulting pattern, as shown in Figure 31.11) is determined by its wavelike behavior. (In later physics courses, we will learn that these waves are probability amplitudes that tell us where a photon is likely, or not likely, to be found.)
Light behaves as a particle (a photon) when it is absorbed and detected.
In summary, experiments compel us to conclude that even single photons have wave properties. This is discussed on pages 588-590.