Potential difference and power — practice question

What are the SI base units for electromotive force (e.m.f.)?

• A$\text{kg m}^2\text{ s}^{-1}\text{ A}^{-1}$
• B$\text{kg m}^2\text{ s}^{-3}\text{ A}^{-1}$
• C$\text{kg m}^2\text{ s}^{-1}\text{ A}$
• D$\text{kg m s}^{-3}\text{ A}^{-1}$