To solve this problem, we need to understand the criteria used for the classification of fungi.$\newline$Fungi are classified based on several characteristics, including:$\newline$• Mode of spore formation: This refers to how spores are produced, which is a key feature in fungal classification.$\newline$• Fruiting body: The structure that produces and releases spores is another important classification criterion.$\newline$• Morphology of mycelium: The structure and form of the mycelium (the vegetative part of fungi) are used in classification.$\newline$• Mode of nutrition: While fungi are heterotrophic, the specific mode of nutrition is not typically used as a primary criterion for classification.$\newline$Analyzing the options:$\newline$• Option 1: Mode of spore formation is a criterion for classification.$\newline$• Option 2: Fruiting body is a criterion for classification.$\newline$• Option 3: Morphology of mycelium is a criterion for classification.$\newline$• Option 4: Mode of nutrition is not a primary criterion for classification of fungi.$\newline$Therefore, the correct option is Option 4.