What does the symmetry rule imply about the state of allosteric enzyme subunits in the concerted model?

• A. Subunits must be in the T state only.
• B. Subunits must be in the R state only.
• C. Subunits can be in different states, some in T and some in R.
• D. All subunits must be in the same state, either all T or all R.

Answer: (D)