An enzyme with higher Kcat/Km ratio is:
More efficient is the accurate response regarding enzymatic activity or regulation described in this question. Enzymes are biological catalysts that accelerate reactions by lowering activation energy through specific substrate binding and transition state stabilization. In the context of Enzyme Kinetics, More efficient plays a specific catalytic or regulatory role determined by its active site configuration and mechanism of action. The other options (Less efficient, Unaffected by substrate concentration, and Only affected by pH) are either different enzymes with distinct substrate specificitie
Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 6