BIOLOGY EXPERTS HELP!!! Which of the following examples poses the greatest potential threat to an ecosystem’s biodiversity?

a) Abandoned farmland is allowed to go fallow and begins to fill in with weeds, shrubs, and saplings.
b) A nonnative species of bee is introduced to prey on the introduced species of fire ants in the Southern United States.
c) A monoculture of fir trees is planted on land that was once clear cut from deforestation.
d) The trapping and relocating of wolves poses a threat as they move into areas of high human population.