How Do Protein Kinases Generally Activate Their Target Proteins

Multiple Choice

How do protein kinases generally activate their target proteins?

A) The process of phosphorylation causes the target to change conformation.
B) The kinases bind to target proteins directly,forming a complex that activates the protein and lets them change conformations.
C) Kinases vary their concentrations through the cell cycle,so that proteins are activated only when kinase levels are high.
D) Kinases bind to target proteins and inactivate them,so kinase levels must drop for target protein activation.
E) The process of dephosphorylation causes the target to change conformations.