The correct option is C Both b and c
Introduction to dikaryophase
Generally during fusion of cell plasmogamy is followed by karyogamy. But in some sexually reproducing Fungi, the plasmogamy is not followed by karyogamy immediately. In such cases an intermediate phase occurs and is called the dikaryophase. During this phase the cell has two nuclei.
This occurs in some of the members of Ascomycetes and Basidiomycetes.
Ascomycetes
Members of the class Ascomycetes like Claviceps, Penicillium, etc., show dikaryophase i.e., two nuclei per cell during sexual reproduction.
Basidiomycetes
During sexual reproduction, members of the class Basidiomycetes like Agaricus, Ustilago, etc., exhibit the intervening dikaryophase.
Final answer
(d) Both b and c