Which type of food has been processed without synthetic fertilizers, sewage sludge, irradiation, or genetic engineering?

Organic food is defined by farming practices that adhere to specific standards aimed at promoting environmental sustainability and reducing exposure to harmful substances. These standards prohibit the use of synthetic fertilizers, sewage sludge, irradiation, and genetic engineering, ensuring a purer form of agriculture. This means that organic food is grown in a manner that fosters biodiversity, soil health, and ecological balance without the harmful chemical interventions often associated with conventional farming methods.

In contrast, conventional food may involve the use of those very practices that organic food avoids, which can include synthetic fertilizers and genetically modified organisms (GMOs). Natural food is often intended to suggest that a product is minimally processed, but it doesn't necessarily certify that the product adheres to the organic standards. Whole food refers to food that is unprocessed or minimally processed but does not provide a guarantee regarding farming practices concerning synthetic substances.

Therefore, the designation of organic food is specific to the strict guidelines that distinguish it from other categories of food, making it the correct answer in this context.