Which is the best organizational structure for a process?

If you refer to the organizational structure of a company, there is no correct answer. Previously it was believed that a linear structure (where power was pyramidal) helped to have a better organization within companies. Nowadays it has been seen that each organization is different and that it must adapt its structure to the specific needs it presents. It is recommended that there is a leading role, either at the head of the entire company, or at the head of the different areas that are managed. Some examples of base organizational structures are the following:

the correct answer would be:  

a. adverb phrase