When we describe electric flux, we say that a surface is oriented in a certain direction with respect to an electric field. When we try to calculate how much electric field passes through the surface, we make use of the:. 1. Wedge Product
2. Dot Product
3. Cross Product

2. Dot Product

Explanation:

The calculation of the electric flux gives an scalar result.

When we tray to calculate how much electric field passes trough a surface, we are calculating a scalar value. Furthermore, the concept of flux requires the calculation of a scalar value.

Also it is necessary to take into account that the magnitude of the flux trough a surface depends of the inclination of the surface respect to the direction of the electric field. This is taken into account sufficiently by a dot product.

Then, the answer is:

2. Dot Product