Mewhat is occurring at point b? select the correct answer below. a. melting /freezing b. boiling /condensing c. boiling /melting d. none of the above

Energy is being put into something, but its temperature isn't changing. It must be a phase-change, but which one ? ?
Well, we can see that there's another one ... Segment D ... and THAT one happens at a higher temperature.
So the other one must be boiling/condensing, and segment-B must be melting/freezing.

Alinear relationship would look like a straight line on the graph. it could have a positive negative or 0 slope. so it could be a line potentially going in any direction but it must be perfectly straight.