An unknown substance is heated from 10 °c to 25 °c. the table below shows the state of the substance at different temperatures.

time
(minutes) temperature of liquid
(degrees celsius) state of matter
0 10 solid
2 15 solid
4 17
6 17
8 17
10 23 liquid
12 25 liquid

which statement is correct about the unknown substance?

its melting point is 17 °c.

its melting point is 15 °c.

the substance sublimes at 15 °c.

the substance exists as a gas at 17 °c.

(this is science)