A photoelectric experiment illuminates the same metal with six different ultraviolet sources. Both the wavelength and the intensity vary from one source to another. Rank the six situations in order of the stopping potential, largest to smallest. 

(a) λ = 200 nm, I = 200 W/m²; 

(b) λ = 250 nm, I = 250 W/m²; 

(c) λ = 250 nm, I = 200 W/m²;
(d) λ = 300 nm, I = 100 W/m²; 

(e) λ = 100 nm, I = 20 W/m²; 

(f) λ = 200 nm, I = 40 W/m².