After karyogamy followed by meiosis, spores are produced exogenously in

In Agaricus, meiospores are produced exogenously after karyogamy and meiosis. This fungus belongs to Basidiomycetes.

Alternaria belongs to the Deuteromycetes class of fungi. The fungi of this class lack sexual reproduction. Therefore, sexual spores are not formed.
Neurospora and Saccharomyces belong to Ascomycetes class of fungi. They produce ascopores as meiospores. Their ascospores are produced endogenously.