Hint: The fern belongs to the Pteridophyta. They are also called vascular cryptogams. It is a member of a group of vascular plants and has neither seeds nor flowers. Ferns are perennial plants, those that live for many years.
Complete answer:The main Plant body of the Pteridophytes is called the sporophytes, which have two sets of chromosomes and are divided into the true roots, the true leaves, and the true stems. The sex organs which are present in them are multicellular. The dominant phase in the life cycle of the pteridophytes is the sporophytic phase and the gametophytic phase is short-lived. The spores are produced inside the sporangia which are present over some of its leaves. These kinds of leaves which contain sporangia are called the sporophylls. These sporophylls form the cone-like structure called the strobili. Ther sporophytes produced spores which gave rise to the gametophytes which, by the mitotic division, formed gametes. These gametes fuse to form the zygote which grows to form the embryo and this further develops into the sporophytes and these sporophytes again produce spores and this cycle continues. Hence it is clear that the fern reproduces through the Spores.
Therefore, the correct answer is option B.
Note: The gametophytes of the pteridophytes can be either monoecious or dioecious. In the monoecious, both the male and the female gametes are produced on the same plant while on the dioecious the male and the female gametes are produced on the different plant.