What type of machine is a ramp for wheelchairs?

a. mechanical machine
b. compound machine
c. simple machine
d. complex machine

i think the answer is terrae but not 100 percent sure. ▓▬▬ §

i don't see a text, but i am gonna assume this *orbit* the curved path, usually elliptical, described by a planet, satellite, spaceship, etc., around a celestial body, as the sun.

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.