B

Step 1: According to Gauss's law, the electric flux $\\Phi_E$ through a closed surface (Gaussian surface) is given by the equation:
$$ \\Phi_E = \\epsilon_0 \\int E \\cdot dS = q_{enc} $$
where $q_{enc}$ is the net charge enclosed by the surface.

Step 2: If the net charge enclosed ($q_{enc}$) is zero, the equation can be rewritten as:
$$ \\Phi_E = 0 $$

Step 3: The electric flux being zero implies that the total incoming electric field lines through the Gaussian surface are equal to the total outgoing electric field lines.

Step 4: Therefore, option B states, "Incoming and outgoing electric lines are equal," which is a direct consequence of the zero net charge: the amount of field lines entering the surface equals the amount leaving it.

Step 5: Options A (E on surface must be zero) and C (there is a net incoming electric flux) do not necessarily hold true. Thus, they are incorrect. Option D (none) is also incorrect as option B is valid.

Therefore, the correct answer is B.