The correct option is D dependent upon the iodine concentration
The rate of iodine uptake by the thyroid is dependent upon the iodine concentration.
When table salt enriched with non-radioactive isotope of iodine is used, the ratio of non radioactive iodine to radioactive isotope of iodine present in thyroid will be higher.
Hence, the ill effects of radioactive isotope of iodine can be minimized.