Answer:
D. The pattern observed indicates that electrons struck the screen in alternating bands across the screen.
Step-by-step explanation:
The moving electrons will behave as wave due to wave - particle duality . These waves will overlap to show interference pattern on the screen . A pattern of alternate dark and bright band which reflects the concentration of electrons at some places and absence of electrons at others are shown. They are akin to interference band made in case of young's double slit experiment.