Would molecular exclusion, affinity, or hydrophobic interaction chromatography be most appropriate for each of the following applications?

(a) Purifying and concentrating a crude mixture of an antibody.
(b) Desalting a solution containing a 30 kDa protein.
(c) Finding the molecular mass distribution of polystyrene with 15 kDa average mass.
(d) Separation of cytochrome c (12 400 Da) and ribonuclease A (12 600 Da). Cytochrome c has lower surface hydrophobicity than ribonuclease A.