The correct option is this: VARIATIONS ARE GREATER OVER LAND THAN OVER WATER.
Temperature variation over water is very small compared to temperature variation over land. This is because, water has high specific heat capacity, which enables it to resist temperature changes when it absorb heat or when it releases heat. A large amount of heat has to be lost or gained before water will show a one degree Celsius temperature change.
Answer: The cause can be something that causes the problem and the effect is what effected it. If something caused the population to go down the effect would be death rate or birth rate.
