The correct option is A Basidiomycetes
A clamp connection is a hook like structure formed by growing hyphal cells of certain fungi belonging to the class basidiomycetes. Sexual reproduction in these fungi results in the formation of a dikaryon (cell with two haploid nuclei) formed a result of fusion of two hyphae of differet mating types. Clamp connections ensure that each hyphae receive a set of different nuclei.
Ascomycetes, saccharomycetes and hyphomycetes do not show the presence of clamp connections.