Question

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

Explanation:

Pioneer species like lichens and mosses secrete acids that break down bare rock. Over time, this physical and chemical weathering process gradually transforms the rock into soil. This soil then becomes suitable for other plant species to colonize, which is a key part of primary succession. The first option is incorrect as rocks don't receive nutrients from pioneer species in that way. The second option is wrong because pioneer species actually help other species colonize later by creating soil.

Answer:

They slowly change the rock into soil.