What does the Lundquist number in plasma physics compare?

A. The timescale of an Alfvén wave crossing to the timescale of radiative cooling
B. The timescale of an Alfvén wave crossing to the timescale of convective transport
C. The timescale of an Alfvén wave crossing to the timescale of thermal conduction
D. The timescale of an Alfvén wave crossing to the timescale of resistive diffusion
Answer: 