the bouncing back of waves as they meet a surface the bending of waves as they pass from one medium to another the bending of waves as they pass an edge or an opening the combining of two waves that meet at a point
I gave my students this multiple choice question: Which of the following describes diffraction?

Only one answer is correct among these 4 choices:
- the bouncing back of waves as they meet a surface
- the bending of waves as they pass from one medium to another
- the bending of waves as they pass an edge or an opening
- the combining of two waves that meet at a point

Could you tell me which one is correct?

the bending of waves as they pass an edge or an opening