Final answer:
Mycorrhizae inside roots are fungi, and orchids have these types of mycorrhizae: ectomycorrhiza, arbuscular mycorrhiza, and a third type unique to orchids.
Step-by-step explanation:
Mycorrhizae inside roots are a) Fungi; orchids have these:
Ectomycorrhiza depend on fungi enveloping the roots in a sheath and a net of hyphae that extends into the roots between cells. In a second type, the Glomeromycota fungi form arbuscular mycorrhiza. In these mycorrhiza, the fungi form arbuscles, a specialized highly branched hypha, which penetrate root cells and are the sites of the metabolic exchanges between the fungus and the host plant. Orchids rely on a third type of mycorrhiza. After nutrients in the seed are depleted, fungal symbionts support the growth of the orchid by providing necessary carbohydrates and minerals. Some orchids continue to be mycorrhizal throughout their lifecycle.