Answer:
Plants and trees which have big or broad leaves are generally found in areas which receive high rainfall like rainforest. It is an adaptation for plants found in such areas. Trees need ample water to grow so big leaves catch the rainfall and funnel it down to the tree's root system, where it is easily absorbed. Rainy regions have a lot of cloud cover and trees here have large leaves which allows them to absorb more of the limited sunlight to perform photosynthesis. Trees here can support large leaves also because they can easily replace the water which the leaves lose to the air.
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