Certain food sources provide more urea than others. Which of the following foods would provide the most urea that would have to be filtered out of the blood via the kidneys?

Urea is formed at the end of a series of reactions which break down the amino acids in proteins. Therefore, urea is a major waste product of protein.
Other types of foods, such as fruits, oils, and grains, are not primarily composed of amino acids, so they would not result in high levels of urea as a waste product after being broken down during digestion.