A 1 meter-long rectangular waveguide is formed by copper walls (1.0 inch x 2.0 inch) and is filled with polyethylene. A 1W, 3 GHz EM wave is injected into the waveguide entrance. What is the peak electric field of the EM wave at the entrance?

there is no correct list among the choices you've provided.

the list might look something like this:

-- baby human

-- piccolo

-- flute

-- soprano singer

-- trumpet

-- tenor singer

-- trombone

-- baritone singer

-- baritone horn

-- bass singer

-- tuba

since i had to make up the list myself, i made it easy on myself, and i didn't try to shuffle the string instruments and woodwinds into it too.