Clamp connection is found in

a. Basidiomycetes

b. Ascomycetes

c. Saccharomycetes

d. Haplomycetes

Option A - Basidiomycota is one of the two major divisions that, together with Ascomycota, forms the subkingdom Dikarya, often referred to as the "higher fungi" within the kingdom Fungi. Specifically, Basidiomycota includes the following groups:

• Mushrooms
• Puffballs
• Stinkhorns
• Bracket fungi
• Other polypores
• Jelly fungi
• Boletes
• Chanterelles
• Earth stars
• Smuts
• Bunts
• Rusts
• Mirror yeasts
• Human pathogenic yeast Cryptococcus

Option B - Ascomycota is a phylum within the Fungi Kingdom that, together with Basidiomycota, forms the subkingdom Dikarya. Members are commonly known as sac fungi or ascomycetes. It represents the largest phylum of fungi, containing more than 64,000 species.

Option C - Saccharomycetes are recognized for comprising a monophyletic lineage consisting of a single order with approximately 1,000 known species. These yeasts function as decomposers, feeding on dead and decaying wood, leaves, leaf litter, and other organic matter.

Option D - Hyphomycetes represent a classification within fungi, forming part of what has traditionally been called Fungi Imperfecti, Deuteromycota, or anamorphic fungi. Hyphomycetes are characterized by their lack of closed fruiting bodies and are commonly referred to as molds.

Therefore, the correct answer is Option A.