Task: Question Answering
Input (English): Question: Van Deemter's velocity equation tries to justify the contributions of the different effects that cause the widening of the chromatographic band, which are basically of four types: 
 Options:  <1> Eddy diffusion, dead volume and resistance to convection in both phases, mobile and stationary. <2> Length of the chromatographic column, longitudinal diffusion in axial and radical direction, and Joule effect. <3> Kinematic viscosity of the mobile phase, mass transport between the mobile phase and the stationary phase, transversal and longitudinal diffusion. <4> Effect of mass transfer in the stationary phase, in the mobile phase, Eddy diffusion and longitudinal molecular diffusion. <5> Molecular diffusion in axial direction, radical atomic diffusion, internal pressure of the column and viscosity of the mobile phase.
Output (English): 4