Question

how do pioneer species (lichens and mosses) contribute to primary succession on bare rock? they slowly change the rock into soil. they feed the rock nutrients. they prevent other species from colonizing.

Explanation:

Pioneer species like lichens and mosses produce acids that break down bare rock. Over time, this weathering process, along with the accumulation of organic matter as these organisms die, gradually transforms the rock into soil. This soil is then essential for the establishment of other plant species during primary succession. The option "They feed the rock nutrients" is incorrect as rocks don't receive nutrients in this way. And "They prevent other species from colonizing" is also wrong because pioneer species actually prepare the ground (by creating soil) for subsequent species to colonize.

Answer:

They slowly change the rock into soil.