The correct association for dense bushes would be Savanna.
Explanation:
The physical setting of Savanna favors the growth of shrubs in abundance. The trees in Savanna are placed on wide distances allowing the sunlight to reach the ground.
This allows and favors the growth of herbaceous layers of grasses and smaller plants like woody bushes.
In a rainforest, the trees are closely placed and in most instances don't allow the sunlight to penetrate through their dense canopies.
