Concept:Edible fungi are safe to eat and used as food. Agaricus (mushroom) is a common edible fungus rich in nutrients.Explanation:Agaricus, known as the mushroom, is a fleshy spore-bearing fungus. It is eaten by humans and contains protein, vitamins, and minerals. It belongs to class Basidiomycetes.Other options are not edible. Albugo causes white rust in crucifers. Pythium causes damping-off disease in plants. Ascobolus is a cup fungus not used as food.Thus, only Agaricus is an edible fungus among the given options.Answer:A. Agaricus