Which of the following is likely to be a response by a receptor protein to an approaching signal molecule?

• A. Recognize the receptor protein having the correct 3-D shape.
• B. Receptor protein binds to signal if having complementary shape.
• C. Once a signal binds to a receptor protein it induces a change in the receptor protein's shape.
• D. Change in the receptor protein's shape results in a cellular response to the signal.
• E. All of the above are correct.