What do b ions and y ions represent in mass spectrometry?

• A. b ions contain the N-terminal residue, y ions contain the C-terminal residue.
• B. Both b and y ions contain the entire peptide sequence.
• C. b ions and y ions are not related to peptide fragmentation.
• D. b ions contain the C-terminal residue, y ions contain the N-terminal residue.

Answer: (A)