Final answer:
A somatic cell mutation occurs in non-reproductive cells and cannot be passed on to offspring. These mutations may result in diseases like cancer but can also be harmless or occasionally beneficial.
Step-by-step explanation:
The true statement concerning a somatic cell mutation is that it occurs in non-reproductive cells. Somatic mutations are alterations that happen in the cells of the body other than the reproductive cells (germ cells like sperm and egg cells). Unlike germline mutations which occur in gametes and can be passed on to offspring, somatic mutations affect only the individual in which they occur and can't be inherited by future generations.
While many somatic mutations are harmless or have little effect, others can cause diseases such as cancer. It's also important to note that somatic mutations are not always harmful; they can occasionally be neutral or even beneficial, depending on their impact on the organism's survival and reproduction.