Question

This entity will be the first one to colonize a bare rock
A. Herbs and shrubs
B. Annual plants
C. Lichens
D. Perennial plants

Answer 1

HINT:
The process by which there are gradual changes in the species or habitat of a given area over time is called ecological succession. These changes will occur till a community is formed that is near equilibrium with the environment. The two types of ecological succession are primary and secondary.

COMPLETE STEP BY STEP ANSWER:
The succession that occurs in an area where no organism ever existed, say a bare rock is called primary succession whereas the succession that occurs in an area that somehow lost all the living organisms that existed there, say an area affected by drought or flood is called secondary succession.
Primary succession is slow as before the establishment of the biotic community, there must be soil and it takes hundreds and thousands of years for soil to be fertile. Secondary succession is fast because it has only lost its biotic components and the soil is still fertile or can be made fertile at a quite faster rate.
Pioneer species are the species that can invade a bare rock. Lichens are the symbiotic relationship between algae and fungi and are the species that can colonize bare rock. Lichens secrete acid to dissolve rock and result in weathering and soil formation. Later some bryophytes that can hold in the small amount of soil can be grown on these rocks which are later replaced by higher plants.
Herbs are plants with green and tender stems whereas shrubs are the small woody plants.
Annual plants are those plants that are grown once a year and show clear-cut vegetative, reproductive and senescent phases. For example; watermelon and chickweed.
Perennial plants are those plants that can live for two or more growing seasons and do not show clear-cut vegetative, reproductive and senescent phases. For example; potato, agave and apple.
Thus, the correct answer is:- Lichens.

Option ‘C’ is correct

NOTE:
The pioneer species with time are replaced by rooted-submerged plants, rooted-floating angiosperms followed by free-floating plants, then reed-swamp, scrub and then finally trees.