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.
Material through which water flows is permeable. This material can be either natural or artificial. Naturally permeable material can be clean sand and gravel for example, or a sandstone and in the latter case the sandstone can have both porosity which is not synonymous with permeability as the pores must be connected to be permeable. An impermeable membrane could be used to line ditches for example to prevent leakage near mines.
Type of neuron that receives messages from the environment is a sensory neuron ie it receives messages from the 5 senses which are used by man to investigate the environment.