The visible part of lichen mostly consists of:

Explanation

Lichens are symbiotic associations between fungi and photosynthetic organisms, usually algae or cyanobacteria. The fungal partner (mycobiont) forms the majority of the lichen's structure, creating a protective environment for the algal partner (photobiont) and absorbing nutrients and moisture. This symbiotic relationship allows lichens to thrive in diverse and often harsh environments. The options 'Epidermis' and 'Cuticle' are unrelated to lichen structure, as they pertain to plant and animal biology.