Which Scenario Would Allow $\beta$ -Arrestin to Bind to the GPCR?
A)

Multiple Choice

Which scenario would allow $\beta$ -arrestin to bind to the GPCR?

A) " $\beta$ ARK is internalized into the endosome."
B) "The receptor is phosphorylated."
C) "G _$\alpha$ is bound to GDP."
D) "The regulatory subunit of $\beta$ -arrestin is removed."