During an experiment, a thermometer is put into a test-tube containing hot liquid. The liquid's temperature is noted every half minute. The table presents the results. What temperature is the substance's melting point?
- A$0\ ^\circ\text{C}$
- B$33\ ^\circ\text{C}$
- C$55\ ^\circ\text{C}$
- D$73\ ^\circ\text{C}$