The Following Questions Refer to the Structure Below

The following questions refer to the structure below:
-To affect cellular change this molecule

A) inhibits the catalytic subunit of protein kinase A
B) binds the regulatory subunit of protein kinase A and inhibits the enzyme's catalytic activity
C) binds the regulatory subunit of protein kinase A and encourages release of the enzyme's catalytic subunits
D) binds G-proteins to activate them when a hormone binds a G-protein coupled receptor