60 points and brainliest!
which segments show changes of state that absorb heat?
b-c
c-d
d-c
d-e
e-f

B-C and D-E  

Explanation:

In segment B-C the substance is changing from a solid to a liquid (melting). There is no change in temperature because the heat is being used to separate the particles from the solid and move them into the liquid phase.

In segment D-E the substance is changing from a liquid to a gas (boiling). There is no change in temperature because the heat is being used to separate the particles from the liquid and move them into the gas phase.

C-D is wrong. The liquid is being heated from its melting point to its boiling point.

D-C is wrong. The liquid is being cooled from its boiling point to its melting point.

E-F is wrong. It represents heating of the gas.

that would be because of both gravity and friction. so     c