At low latitudes, the only interruption to tropical rainforest climates results from

At low latitudes, the only interruption to tropical rainforest climates results from the high altitude.
Only the places that are on a very high altitude are interrupting the chain of rain forests in the low latitudes. There's a certain point to which this type of climate is sustainable, so anything above that line belongs into another climate type and the rain forests are interrupted by this places. 

C. naturally in the environment

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