The correct option is B Mainly by climate
The vegetation of a particular locality depend upon the climatic conditions prevailing in the area. India has a varied range of climate which supports the growth of various species. The different climatic zones are a rich source of biodiversity and an asset for our environment. The extreme climate any adversely affect the vegetation. Although, the vegetation of the places having the extreme climates adapt themselves according to the climatic variations like cactus survives in extreme climate by several adaptations.