How Might You Distinguish a Sodium-Vapor Street Lamp from a Mercury-Vapor

Multiple Choice

How might you distinguish a sodium-vapor street lamp from a mercury-vapor street lamp?

A) use binoculars to look for printing adjacent to the bulb
B) look at the street lamps through a spectroscope and match their spectral patterns to their respective atomic spectra
C) ask your local utility company to identify these lamps for you
D) The shadows cast from a sodium-vapor street lamp tend to be more diffuse around the edges.