A Competitive Antagonist for a Ligand

A competitive antagonist for a ligand

A) Does not interfere with the action of the ligand
B) Blocks the binding of the ligand to its binding site and prevents activation of the protein
C) Causes covalent modulation of the ligand, usually by phosphorylation or dephosphorylation
D) Both blocks the binding of the ligand to its binding site and prevents activation of the protein and causes covalent modulation of the ligand, usually by phosphorylation or dephosphorylation are correct
E) None of the choices are correct