Here the passage is asking, " what can be inferred ? ", i.e. it's asking about the hidden conclusion of the passage. Why not Option A ? - because it is clearly given in the passage : "The exact reasons for the formation of this gap are not clear ". Why not Option B ? - because the passage no where talks about the low-lying regions of Kerala and Tamil Nadu near the Palghat Gap. Why not option D ? - Because the passage only says : "neighbouring regions of Kerala having higher summer temperatures", it doesn't say that this high temperature results in rainfall. Note: We have to think and conclude only from what is given in the passage. We can't make our own conclusions. Why Option C ? - because the passage says : " It results in the neighbouring regions of Tamil Nadu getting more rainfall from the South West monsoon and the neighbouring regions of Kerala having higher summer temperatures", hence we can conclude here that the weather is getting affected due to the Gap. Therefore, option C is correct.