**Core Concept**
The question is testing the knowledge of the permissible limit of iodine in salt as per the Pre-National Programme for Control of Iodine Deficiency Disorders (NPCIDDS) also known as the Pre-Natal Diagnostic Techniques (PNDT) Act, which is enforced by the Prevention of Food Adulteration (PFA) Act.

**Why the Correct Answer is Right**
The permissible limit of iodine in salt is 30-40 parts per million (ppm) as per the World Health Organization (WHO) recommendation. This level is essential to prevent iodine deficiency disorders, including goiter, cretinism, and hypothyroidism. The iodization process involves adding potassium iodate or potassium iodide to salt to achieve this level.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the question about iodine levels in salt.
**Option B:** This option is incorrect as it is not the correct level of iodization as per the PFA Act.
**Option C:** This option is also incorrect as it does not represent the correct level of iodine in salt.

**Clinical Pearl / High-Yield Fact**
It is essential to note that excessive iodine intake can lead to iodine-induced hyperthyroidism, also known as Jod-Basedow phenomenon. Therefore, it is crucial to maintain the optimal level of iodization in salt.

**Correct Answer:** C. 30 ppm.