Siemens is the unit of_________.

Correct option is C

Siemens (S) is the SI unit of electric conductance, which is the measure of how easily electricity flows through a material.
It is the reciprocal of resistance (measured in ohms), and the relationship is given as:

​$$\text{Conductance} (G) = \frac{1}{\text{Resistance} (R)}$$

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Permittivity: Related to the ability of a material to permit electric field lines (measured in farads per meter, F/m).