Answer:
condensation, boiling, melting and even sublimation.
Explanation:
A phase diagram is a graphical illustration of the physical state of matter(solid, liquid and gases) under different sets of temperature and pressure conditions.
In the diagram, at point B, all the phase changes occur. Point B is called the triple point of the substance. At the triple point, water exists as solid, liquid and gases. Here, we have condensation, boiling, melting and even sublimation.
Freezing is a phase change from liquid to solid. Melting involves a change from solid to liquid. Sublimation is from solid to vapor. Condensation is a change from vapor to liquid.
At the triple point, all these changes occur in equilibrium.
