Define Electric Flux 

Question

$\begin{array}{1 1} (a)\;\phi= \overrightarrow{E} . \overrightarrow{ds}\\ (b)\; \phi= \overrightarrow{E} \times \overrightarrow{ds}\\ (c)\;\phi=\large\frac{E}{S} \\(d)\;\phi= \large\frac{\overrightarrow{E} .\overrightarrow{ds}}{2} \end{array}$