Q: Fact 1: Temperature changing can cause phase changes. Fact 2: Melting is the change of phase from a solid to a liquid. Given the two facts above, what can cause melting?

OPTIONS:
(1). Changing pressure
(2). Heat energy
(3). Water expanding
(4). Evaporation
(5). converting electricity to heat
(6). Increase in mass
(7). Temperature changing
(8). Chemical reaction
A:
(7).