Mycorrhizae is the example of?

A lichen is a symbiotic organism. It appears similar to a plant, but it is actually made up of two separate organisms, a fungus and cyanobacteria. The fungus transports water and nutrients to the cyanobacteria which then stores glucose for use by the fungus.Using a plant as your reference, which of the following statements would be the most accurate comparison to help someone understand the relationship between the fungus and cyanobacteria?   The cyanobacteria acts as the ground tissue while the fungus acts as the vascular tissue.    The cyanobacteria functions as the roots while the fungus is similar to the flower of a plant.   The cyanobacteria acts as the meristematic tissue and the fungus acts as the ground tissues.   The cyanobacteria is similar to the xylem in a plant and the fungus is similar to the phloem in a plant.

A lichen is a symbiotic organism. It appears similar to a plant, but it is actually made up of two separate organisms, a fungus and cyanobacteria. The fungus transports water and nutrients to the cyanobacteria which then stores glucose for use by the fungus. Using a plant as your reference, which of the following statements would be the most accurate comparison to help someone understand the relationship between the fungus and cyanobacteria?

What steps would it take for a fungus to establish a symbiotic relationship with plants?  I understand that there are symbiotic soil fungi that are entangled amongst plant roots but this question I am wondering how they form a relationship if the fungus live between the plant cells.