To make a line graph of an object's displacement versus time, you must complete the following steps. place them in the order in which they should be done.

To make a line graph of an object's displacement versus time, you must complete the following steps:
1) Decide the axis with time on x-axis and displacement on y-axis. Do correct labelling.
2)Determine a scale 
2)Plot the points correctly on the graph accordingly
3)Connect the points through a smooth line
 

The correct answer is  "c".  it is "c" because melting is an endothermic change, and endothermic get's energy from surroundings. 

Letter a, because when there are unlike charges they will always attract to each other.