An engineering student is studying the effects of cryogenic treatments on a particular material. the treatment involves cooling the material with
specific applications of liquid nitrogen
the temperature of the material in degrees celsius, y, can be modeled by the following graph, where x represents the time, in hours, since the
treatment began

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.

answer: a and b

step-by-step explanation:

but there’s no any figure there!