Different scholars have approached administrative law from different angles, some from a rule-of-law perspective, some from a control perspective, and identifying the right one means matching the quoted emphasis to the right thinker.
Matching the specific emphasis on agencies and judicial review to its actual source points to Davis.
\[ \boxed{\text{K.C. Davis}} \]Since this is a case of matching a direct quotation to its author, it helps to note the distinctive phrase "judicial review of administrative action" and ask which scholar built his definition around exactly that idea.
The distinctive reference to judicial review of administrative action as part of the very definition points to Davis as its author.
Hence, the correct answer is K.C. Davis.