Can someone help me with this problem?!?!

What does a particular point on a line of a phase diagram represent? o a. the maximum temperature a substance can exist at without bonds breaking b. the pressure created by the kinetic energy of molecules at a particular temperature c. the melting point or boiling point of a substance at a specific pressure d. the conditions in which temperature and pressure have equal effects on a substance

Arollercoaster car at the top of a hill has potential energy kinetic energy chemical energy light energy

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins