The diagram below shows part of the biological life cycle of Giardia intestinalis (syn. Giardia lamblia).  The correct description of the listed events is:

(a) 1=excystation; 2=division by binary fission; and 4=sporulation
(b) 1=excystation; 2=mitosis; and 4=gametogenesis
(c) 1=excystation; 2=division by binary fission; and 4=encystation
(d) 1=encystation; 2=division by binary fission; and 4=excystation