Final answer:
Both ascomycetes and basidiomycetes produce spores, but ascomycetes produce spores in an ascus, while basidiomycetes produce them in a basidium. None of the options provided are features characteristic of both groups simultaneously.
Step-by-step explanation:
The characteristic feature of both ascomycetes and basidiomycetes is the production of spores, but they do so in different structures. Ascomycetes produce their spores in a sac-like structure called an ascus, which is the defining feature of this group. Basidiomycetes, on the other hand, produce their spores in a club-like structure called a basidium. Both ascomycetes and basidiomycetes may form complex fruiting bodies, such as mushrooms in basidiomycetes, and these serve to aid in the dispersal of the spores.
Given the provided options, neither the production of spores in a sac-like structure nor in a club-like structure is a characteristic feature of both groups, as each pertains to one group specifically. Production of spores in a capsule is also not a shared characteristic, as it refers to other taxa. The production of spores in a conidium, which is an asexual spore-bearing structure, is something that is seen in some ascomycetes, but it is not a feature of basidiomycetes.