USDA quality grading of beef is based upon which three factors?

The correct answer is based on the understanding of the USDA quality grading system, which primarily evaluates beef to determine its tenderness, juiciness, and flavor profile. The three main factors that the USDA considers are yield, age, and marbling.

Marbling refers to the intramuscular fat found within the meat, which significantly contributes to the flavor and juiciness of the beef when cooked. The age of the animal is also a critical factor because younger animals typically yield more tender meat than older ones, as meat tends to become tougher with age. Yield indicates the amount of edible meat on a carcass, influencing the overall value and quality assessment of the beef.

Other options include elements that do have relevance in various culinary or grading contexts, but they don't specifically align with the USDA's criteria for quality grading. For example, flavor is an important aspect but not a direct factor in the USDA grading criteria, which is more focused on measurable traits like marbling and age.