Answer:
The correct option is C.
Step-by-step explanation:
It is given that the temperature of the material in degrees Celsius, y, can be modeled by the following graph, where x represents the time, in hours.
From the given graph it is clear that
1. The y-intercept is 40, so the initial temperature is 40 degree Celsius.
2.The vertex of the upward parabola is at (15,-200), so material's temperature reaches a minimum -200 degrees Celsius at 15 hours.
3. The material return to its initial temperature after 30 hours because the temperature is 40 degree Celsius at x=30.
Therefore the correct option is C.
