Official Explanation
The information between the dashes provides extra information about the word just before: “fresh produce has become” available everywhere. The best match is “ubiquitous” (existing everywhere). Neither “salubrious” (healthful) or “comestible” (edible) fits the required meaning. For the second blank “were once the inevitable result of nutritional deficiencies,” diseases, or “maladies,” fits. Neither “reactions” nor cultivars” (cultivated plants) would be “the inevitable result of nutritional deficiencies.” Finally, these once “inevitable” diseases are now mostly avoidable because people have better access to fresh produce. The best match is “preventable.” “Organic” and “dietetic” (relating to the diet) are both related to food but don’t match the meaning of “avoidable.”
Answer: B,D,I