Which of the following is an example of primary succession by inhibition?
a. Black walnut trees secreting toxic chemicals into the soil after a flood that prevents the growth of other plant species
b. The tree, Trema, in the middle of an abandoned pasture in Brazil providing branches that fruiteating birds can perch on and defecate seeds of other tree species
c. Lichens that colonize the glacial till from the melting Thwaites Glacier in Antarctica and prevent the gemination of later successional shrub seeds.
d. Lupine plants with nitrogen fixing bacteria in their roots colonizing a lava flow on Mt St Helens in Washington increase the level of soil nitrogen that other plant species can use