In bluegill fish populations three different reproductive morphs (parental, sneaker, and satellite) ...

In bluegill fish populations three different reproductive morphs (parental, sneaker, and satellite) coexist. What is a potential ultimate reason for the coexistence of these morphs?
 
  a. The populations are polymorphic for parental, sneaker, and satellite alleles.
  b. An immature male's nutritional status triggers parental, sneaker, and satellite developmental pathways.
  c. Successful parental males must exert substantial amounts of energy for brood care and defense; nutritionally disadvantaged males may optimize their fitness by becoming sneaker males instead.
  d. The fitness of cheaters like sneaker and satellite males is frequency dependent.
  e. C and D.