The correct answer is (c) Small amounts of a mutagen often do not have an effect on health.
The doctor will explain that small amount of mutagen(x-ray) often do not have any severe health issues. Radiologists are trained to use the optimal amount of x-rays required for the procedure and this amount is very less. Properly carrying out the whole procedure minimizes the risk. The amount of radiation used is small and is turned off soon after the procedure is completed. So, small amount of x-ray exposed for a very short period of time is not risky.