A temperature at which both solid and liquid state of water are present in equilibrium is known as melting point and the temperature remains constant during this transition of phase.
As it is shown in the graph that temperature at point A is zero degree celsius that is, the temperature at which water freezes completely. And, point B shows that solid and liquid phase are in equilibrium. This means that the temperature at point B is also zero degree celsius.
Hence, we can conclude that temperature at point B is , because it is the melting point of ice.
Point B is the temperature at which the water is converted from ice (solid phase) to liquid water (liquid phase), which is the melting transition of water.
Melting point of the water is at 0.0°C.
<em>So, the right choice is: A) 0 °C, because it is the melting point of ice. </em>
