Research Summary. A multi-factor catalase concentration test investigation used five groups, but not every possible treatment combination was included. Table 1 (Catalase Concentration Test Multi-Factor Design) lists Catalase Concentration Trial A (enzyme concentration: 4%; hydrogen peroxide concentration: 3%; temperature: 35 degrees C; bubble height: 52); Catalase Concentration Trial B (enzyme concentration: 4%; hydrogen peroxide concentration: 3%; temperature: 20 degrees C; bubble height: 48); Catalase Concentration Trial C (enzyme concentration: 4%; hydrogen peroxide concentration: 1%; temperature: 20 degrees C; bubble height: 44); Catalase Concentration Trial D (enzyme concentration: 1%; hydrogen peroxide concentration: 1%; temperature: 35 degrees C; bubble height: 40); Catalase Concentration Trial E (enzyme concentration: 1%; hydrogen peroxide concentration: 1%; temperature: 20 degrees C; bubble height: 37). Which pair provides the cleanest comparison for the treatment factor enzyme concentration?