The gametophyte of lycopsida is mainly:

Explanation

In the plant group Lycopsida, which includes clubmosses, spike mosses, and quillworts, the gametophyte generation is predominantly underground. This generation is typically small and non-photosynthetic, obtaining nutrients through symbiosis with fungi. This contrasts with the sporophyte generation, which is the dominant, visible phase that carries out photosynthesis and produces spores. Thus, the correct answer is that the gametophyte of Lycopsida is 'Underground'. The other options are incorrect because they do not accurately describe the typical habitat or characteristics of the Lycopsida gametophyte.