At a Distance $d$ From a Point Charge $Q$ , the Energy Density in Its Electric Field Is

Multiple Choice

At a distance $d$ from a point charge $Q$ , the energy density in its electric field is $u$ . If we now go to a distance $d / 2$ from the charge, what is the energy density at the new location?

A) $8 u$
B) $16 u$
C) $4 u$
D) $2 u$
E) $u \sqrt { 2 }$