In class we have discussed that there are two types of correlation involved in the diffusion of atoms and ions in solids. a) Briefly explain these two types of correlation. b) Consider the diffusion of a tracer A* in an A-B alloy at different concentrations of A, i.e., at xA = 0, 0 < xA < 1 and xA = 1. Which type of correlation plays a role in the diffusion for the different concentrations xA