Which is not a medium through which a mechanical wave could travel? liquid water jump rope oxygen gas empty space

Mechanical Wave cannot travel in space vaccumes, which would be considered "Empty Space" in your situation.

A mechanical cannot travel through empty space. So option (d) is correct.

A mechanical wave is a wave which needs a material medium for its propagation. For example sound, water waves etc . The medium required by the wave can be a solid, liquid or a gas. Empty space doesn't have any medium, so a mechanical wave cannot travel through empty space.

(75°f − 32) × 5/9 = 23.889°c

this is a good question! i'll do some research and come back when i have the answer!