The process of generating monoclonal antibodies is labor-intensive and expensive. An alternative is to use polyclonal antibodies. A subpopulation of purified polyclonal antibodies that recognize a particular antigen can be isolated by chromatography. Which type of chromatography is used for this purpose?
(a) affinity
(b) ion-exchange
(c) gel-filtration
(d) any of the above
Answer: A