Cheatgrass Has Been Able to Invade Dry,temperate Grasslands and the Arid,shrub-Dominated

Multiple Choice

Cheatgrass has been able to invade dry,temperate grasslands and the arid,shrub-dominated habitats (sage-steppe) of North America.Which of the following is not a reason for this?

A) Cheatgrass is an annual,so there are seeds in the ground ready to grow any year.
B) Cheatgrass is somewhat fire tolerant.
C) Cheatgrass promotes fire frequency and increases fire intensity.
D) Cheatgrass competes successfully with bunchgrasses for water and nutrients.
E) All of the above are valid reasons.