Concept:Increasing pressure lowers the melting point of ice, causing it to melt and refreeze when pressure is removed.
Explanation:Water expands when it freezes into ice.
So increasing pressure on ice makes melting easier because melting allows the ice to occupy a smaller volume.
Thus, ice under high pressure melts at a temperature below its normal melting point.
When the pressure is released, the melted water refreezes again.
This melting under pressure and refreezing after pressure is removed is called regelation.
This is clearly observed when a weighted wire slowly passes through a block of ice without cutting it into two pieces.
Answer:The correct option is D. regelation.