Which of the following best describes an effective adaptation of plants commonly found in the rain forest?

Plants in the rain forest have unique adaptations to help them to thrive in the climatic conditions present there. Temperatures in the rain forest are high all year round. Since tropical rain forests are located around the equator they receive direct sunlight. The leaves of the plants here are waxy to protect them from the direct sunlight. 
Rain fall is high here and it can get up to 4000 mm per year. Leaves are equipped with drip tips to allow for the easy run off of water after a down pour.
The barks of most trees are also smooth to further facilitate the movement of water to the ground. The trees in the forest grow fast and compete with each other for sunlight. The trees grow very tall and very fast so they have specialized roots called buttress roots that can support them. These roots spread out to support tall trees. 
The dense vegetation of the forest prevents much plants from growing under the canopy of the trees. A small number of plant however can survive in this low light environment. The plant that grow under the canopy have large, dark green leaves to make use of the little light that passes through.