The Appropriate Sequence for Ubiquitination of Proteins to Be Degraded

The appropriate sequence for ubiquitination of proteins to be degraded is:
A.multiple ubiquitinations may occur on a protein substrate,
B.ubiquitin-protein ligase (E₃) transfers ubiquitin to free amino groups on the protein,
C.E₃ selects a protein for degradation by the nature of the N-terminal amino acid,
D.ubiquitin-carrier protein (E₂) picks up ubiquitin,
E.ubiquitin-activating enzyme (E₁) attaches via ATP-dependent formation of thioester bond to C-termini of ubiquitin,

A) A, C, B, D, E
B) E, D, A, B, C
C) D, E, C, A, B
D) C, E, D, B, A
E) E, D, C, B, A