Final answer:
A plant with seeds not in a flower or fruit is known as a Gymnosperm. This includes conifers and similar plants with seeds that are exposed, unlike the enclosed seeds of angiosperms. Mosses and ferns do not produce seeds and are not gymnosperms.
Step-by-step explanation:
A plant whose seeds are not in a flower or fruit is a Gymnosperm. Gymnosperms are a diverse group of seed plants characterized by seeds that are not enclosed by a fleshy fruit. This group includes familiar plants such as conifers (spruce, fir, and pine) as well as ginkgos and cycads.
Unlike angiosperms, which are flowering plants with seeds enclosed in fruit, gymnosperms reproduce with separate female and male gametes and often rely on wind for pollination.
Bryophytes, such as mosses, and seedless vascular plants like ferns, do not produce seeds at all and reproduce via spores. The correct option is C.