d) All of the above are possible threats to human health due to global warming.
A) because: less land (humans generally have to be on land (as a boat cannot last forever)
B) humans need to drink water, and with droughts, we will die of dehydration. Other natural disasters will cause casualties as well.
C) With the extinction of animals and plants, the food-chain/food-web would be disrupted, leading to mass-extinction of many animals and plants
hope this helps