Which of the following relationship is NOT an example of symbiosis?

Explanation

The relationship between a Marchantia sporophyte and gametophyte is an alternation-of-generations relationship within one plant life cycle, not symbiosis between separate organisms. Rhizobium with legumes, algae with fungi in lichens and mycorrhizal fungi with roots are classic close associations between different organisms. Students may choose a because Rhizobium is sometimes described as parasitic in other contexts, but its usual association with legumes is mutualistic symbiosis.