Which statement about the interference behavior of electromagnetic radiation seen in the double-slit test experiment is true?
1. Waves that make up the radiation do not interact with each other.
2. Particles that make up the radiation collide with each other and scatter randomly.
3. Particles that make up the radiation collide with each other so that they add together or cancel each other out.
4. Waves that make up the radiation collide with each other so that they add together or cancel each other out.