Answer: The correct answer is -
Ultraviolet (UV) radiation.
Mutagens are the physical, chemical, or biological agents that are present in the environment and cause mutation (permanent change in the genetic material that is DNA).
UV radiation (present in the sunlight) is considered to be strong mutagen that is absorbed by DNA and cause damage to it (for instance, it forms pyrimidine dimers that later on cause uncontrolled cell division).
It can cause uncontrolled division in the skin cells, which leads to skin cancer.
Thus, UV radiation is the most common mutagen that we become exposed to when we are outside in the sunlight.
