Melting
we know that ice melts at 0 ⁰C. in the graph, at position B, the temperature is constant, which indicates that phase change is taking place there. at B , from the graph , we also notice that the temperature is constant at value 0 ⁰C. this indicates that ice at 0 ⁰C is converting to water at 0 ⁰C there at position B in the graph.
hence the correct choice is Melting.
There are approximately 3 different types of atoms that are present in one molecule of aluminum hydroxide, AI(OH)3.