To give an idea of sensitivity of the platypus's electric sense, how far from a 80nC n C point charge does the field have this magnitude

The question is incomplete. The complete question is :

A platypus foraging for prey can detect an electric field as small as 0.002 N/C.

-To give an idea of sensitivity of the platypus's electric sense, how far from a +80nC point charge does the field have this magnitude?

Solution :

Given electric field,  E = 0.002 N/C

Charge, Q = + 80 nC

or

   R = 600 m

This is the distance of the charge from the point of observations.

whichever one it is, it's definitely not one that you included on the list you provided.

current flows in a wire