If you measure 20 feet between an existing box and a new box location, you should cut a piece of cable with a length of approximately
A. 20 to 21 ft.
B. 25 to 26 ft.
C. 40 to 42 ft.
D. 48 to 55 ft.

A. 20 to 21 ft.

Explanation:

You measured 20 feet from point A to point B, simple so its around 20 feet and some extra inches possibly to account for miscalculations somehow.

Now unless we're surrounding a box or doing more you really shouldnt need anything more.

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.