Which of the Following Best Represents the Sequence of Steps $\rightarrow$

Which of the following best represents the sequence of steps following the activation of a metabotropic receptor?

A) Activation of G protein $\rightarrow$ change in activity of effector enzyme $\rightarrow$ activation of protein kinase $\rightarrow$ change in second messenger levels
B) Activation of G protein $\rightarrow$ change in second messenger levels $\rightarrow$ change in activity of effector enzyme $\rightarrow$ activation of protein kinase
C) Change in second messenger levels $\rightarrow$ change in activity of effector enzyme $\rightarrow$ activation of protein kinase $\rightarrow$ activation of G protein
D) Activation of G protein $\rightarrow$ change in activity of effector enzyme $\rightarrow$ change in second messenger levels $\rightarrow$ activation of protein kinase