Final answer:
The correct option ios a. Ground pines reproduce asexually through small rhizomes, which are underground stems that can develop into new sporophytes. This form of vegetative reproduction is different from bulbils, stolons, or tubers, which are other plant structures that can also lead to asexual reproduction. Rhizomes are the correct answer in this context.
Step-by-step explanation:
A number of ground pines reproduce asexually by means of small bulbils, each of which is capable of developing into a new sporophyte. Ground pines, as well as various other plants, have evolved several mechanisms for asexual reproduction. Reproduction can occur through rhizomes, which are actually stem structures that grow laterally underground, while stolons, also known as runners, grow at or just below the soil surface and can lead to new plant growth as well. Tubers, like potatoes, are another form of stem that can lead to the formation of new plants.
It's important to differentiate between these various forms of asexual reproduction. For instance, rhizomes are horizontal underground stems that can give rise to new plants. Stolons are horizontal stems that grow along the soil surface, giving rise to new plants at the nodes. Tubers are swollen, fleshy, underground stem structures that store food and can give rise to new plants from buds or 'eyes'. Among these options, the correct answer for a structure enabling ground pines to reproduce asexually by developing into a new sporophyte is rhizomes.