Electric field is the electrostatic force per unit charge acting on a vanishingly small test charge placed at that point. It is a vector quantity and the electric field inside a charged conductor is zero. Electric flux f is the total number of electric lines of force passing through a surface in a direction normal to the surface when the surface is placed inside the electric field
We have a Gaussian of radius R with Q at the centre then

Options

A. The total electric flux of the sphere is `phi=-Q/epsilon_0`
B. On the surface of the sphere, we have `E=(-Q)/(4piepsilon_0R^2)`
C. Flux through the surface of sphere due to 5Q is zero.
D. Field on the surface of sphere due to -2Q is same everywhere.