Coal sample analysis has shown the presence of pollen grains. Justify

If in the analysis a coal sample has been found pollen grains, it is because the coal originates from organic matter, such as vegetal matter.

Explanation:

Coal is the product of the accumulation of plant matter that has been deposited in lagoons, shallow lakes or swamps, which by bacterial action is slowly degraded. In the course of time, the content of elemental carbon increases, originating the mineral carbon that remains deposited in the soil.

Since coal is formed by plant matter, it is possible to find in its composition preserved plant remains, such as pollen grains.  Palaeoethnobotanists have found fossils of pollen grains both in the soil and in the deposits of some minerals, like coal.

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

clumped distribution, because you'de have all of the population gathered in a relatively small are.

it's the most common because it provides protection and a mate for reproduction

example: humans, seeweed, cattles, etc.