## Core Concept
The Prevention of Food Adulteration (PFA) Act is a legislation aimed at ensuring the purity and safety of food products, including iodized salt, for human consumption. Iodine is a critical micronutrient added to salt to prevent iodine deficiency disorders. The specified level of iodine in iodized salt is crucial for public health.

## Why the Correct Answer is Right
The correct answer, **15 ppm (parts per million)**, is the mandated level of iodine in iodized salt at the production level. Iodine is added to salt to combat iodine deficiency, which can lead to conditions such as goiter, hypothyroidism, and cretinism. The specified iodine level ensures that the salt provides an adequate amount of iodine for daily consumption, supporting thyroid function and overall health.

## Why Each Wrong Option is Incorrect
- **Option A:** 5 ppm - This level is too low and does not meet the standard requirement for iodine in iodized salt, which is aimed at preventing iodine deficiency disorders.
- **Option B:** 10 ppm - Although closer, this is still below the specified standard, which is crucial for ensuring sufficient iodine intake.
- **Option D:** 20 ppm - While higher levels might seem beneficial, the specified standard is **15 ppm**, making this option excessive in this context.

## Clinical Pearl / High-Yield Fact
A key point to remember is that iodized salt typically contains **15-20 ppm** of iodine to account for losses during storage and transportation, ensuring that by the time it reaches consumers, it still provides an adequate iodine level. The **15 ppm** minimum at production level helps achieve this goal.

## Correct Answer: C. 15 ppm.