A beautiful rainbow in the sky is created through a combination of various optical phenomena involving sunlight and water droplets. Let`s analyze each option:

Option 1 suggests that a rainbow is solely due to the dispersion of sunlight from a water droplet. However, this is an incomplete explanation. While dispersion is one of the factors contributing to a rainbow`s formation, it alone does not account for the complete phenomenon.

Option 2 proposes that a rainbow is caused by the reflection of sunlight from a water droplet. While reflection does play a role in creating a rainbow, it is not the only factor involved.

Option 3 states that a rainbow is formed by both reflection and refraction of sunlight from a water droplet. This is a more accurate description than the previous options. Both reflection, which occurs when light bounces off the droplet`s surface, and refraction, which happens when light bends as it enters and exits the droplet, are essential processes for creating a rainbow.

Option 4, the correct answer, suggests that a rainbow is the result of refraction, dispersion, and reflection of sunlight from a water droplet. This option provides a comprehensive explanation. Refraction causes the sunlight to change direction as it enters and exits the droplets, dispersion separates the light into