Which of the following is a reproductive feature of cycle for Sac Fungi?

The reproductive feature of fungi in the Sac Fungi group, also known as Ascomycetes, is best represented by the formation of structures referred to as ascospores. These ascospores are formed within a sac-like structure called an ascus, and typically occur in groups of eight.

This characteristic distinguishes Sac Fungi from other fungal groups. In a typical life cycle, following sexual reproduction, each ascus contains eight spores that will eventually disperse to form new organisms. This method of reproduction allows for a range of genetic variation, which is crucial for adaptation and survival in diverse environmental conditions.

Other choices involve aspects that are not primarily associated with the reproductive cycle of Sac Fungi. For example, single-cell division broadly refers to asexual reproduction across various organisms, not specific to Sac Fungi. The formation of zygospores is a feature of Zygomycetes, while filamentous structures refer to the mycelium present in many fungi but do not specifically describe the reproductive characteristic of Sac Fungi. Therefore, grouping of eight sex cells in the form of ascospores is the most defining reproductive feature for Sac Fungi.