Which of the following statements is incorrect about electrostatics of conductors?

Options

A. If you are inside a charged conducting box, you can safely touch any point on the inside walls of the box without being electrocuted.
B. Electric field intensity at the surface of a charged conductor `vec E = sigma /epsilon_0 (hat n) ` , where `sigma` is surface charge density and ` hat n` is a unit vector normal to the surface in outward direction.
C. Inside a conductor electrostatic field is zero.
D. The interior of a cavity free conductor can have excess charge in the static situation.