Which of the following is an example of fortification?

Fortification refers to the process of adding nutrients to food items that may not naturally contain them, with the aim of improving nutritional value and reducing the risk of deficiencies in the population. The addition of vitamin D to milk exemplifies this concept, as milk is not a natural source of this vitamin. By fortifying milk with vitamin D, it helps improve bone health and prevent conditions such as rickets, especially in populations that may have limited sun exposure.

The options that involve fiber, restoring nutrients, or adding sugar focus on different aspects of food enhancement or adjustment, but they do not align with the strict definition of fortification. Fiber is an enhancement rather than a nutrient typically added for deficiency prevention. Restoring iron in enriched rice refers more to the enrichment process, where certain nutrients lost during processing are restored rather than newly added nutrients. Adding sugar to cereals is more of an adjustment for taste than a nutritional fortification, as it does not address deficiency prevention.