Do you know what the correct choices are?

Yes, I do !  Please mark me Brainliest.

As the man walks up the mountain, his weight decreases slightly, because he's moving farther away from the center of the Earth, so the gravitational forces between him and the earth are decreasing slightly.

The man is sweating bullets, and maybe losing a little bit of body mass from the extreme exertion. (I know I sure would.)  But as far as gravity is concerned, his mass (matter) is not changing.  Gravity has no effect on mass.

d) physical means can be used to separate the components of air.