Final answer:
A mutation that occurs naturally without exposure to a known mutagen is called a spontaneous mutation.
Step-by-step explanation:
Errors in the replication or repair of DNA, as well as other innate biological processes, can result in spontaneous mutations. The genetic code may alter as a result of these haphazard mutations. Spontaneous mutations are not caused by external agents, chemicals, or radiation exposure, among other factors.
Although spontaneous mutations are a natural component of evolution, they can also increase genetic variety and, in certain situations, be linked to illnesses or disorders. In general, they arise spontaneously from biological activities taking place inside the cell.