Which of the following statements about urea is correct?
- AUrea is formed from excess amino acids in the kidneys and excreted by the liver.
- BUrea is formed from excess glucose in the liver and digested by the kidneys.
- CUrea is formed from excess glucose in the kidneys and excreted by the liver.
- DUrea is formed from excess amino acids in the liver and excreted by the kidneys.