Step 1: Understanding thermal conductivity.
Thermal conductivity \( k \) has the SI units of watts per meter-kelvin (\( \text{W}/(\text{m} \cdot \text{K}) \)), where:
- \( W = \text{J/s} \),
- \( J = \text{kg} \cdot \text{m}^2/\text{s}^2 \).
Step 2: Conclusion.
The dimensions of thermal conductivity \( k \) are \( [M L^2 T^{-2} A^{-1}] \), which corresponds to option (C).