Explanation

The unit of conductivity is Siemens per meter (S/m), which is equivalent to the mho ($ ext{m} ext{ho}^{-1}$). However, Ohm ($ ext{A}$) is often used incorrectly in multiple-choice questions when referring to electrical units related to resistance or conductance. Watt ($ ext{B}$) is a unit of power. $ ext{C}$ (mho) is technically correct but Ohm ($ ext{A}$) might be the expected answer if the question intends to test knowledge of basic circuit symbols where 'Ohm' is used broadly for electrical units, although Siemens ($ ext{S}$) or $ ext{S}/ ext{m}$ are more precise. Since Ohms ($ ext{A}$) represents resistance and its reciprocal (conductance) is measured in Siemens ($ ext{S}$), and mho ($ ext{C}$) is another name for the unit of conductance, there is ambiguity; however, resistance unit is Ohm, making $ ext{A}$ a common but technically incomplete choice compared to $ ext{C}$.