A number of angiosperms have a variety of modified roots: root tubers, aerial roots, etc. What is the reason for the appearance

A number of angiosperms have a variety of modified roots: root tubers, aerial roots, etc. What is the reason for the appearance of various roots? On what path of evolution did plants with such organs evolve?

1) as a result of the mutation process, various changes in the roots appeared
2) natural selection reinforced useful traits
3) the development of plants follows the path of idioadaptation, the emergence of adaptive changes to specific environmental conditions

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