Which of these three lenses offers 

(a) the highest resolution and

(b) the lowest resolution: 

(i) \(f=10 \mathrm{~mm}, d=8 \mathrm{~mm}\); (ii) \(f=15 \mathrm{~mm}, d=10 \mathrm{~mm}\), (iii) \(f=20 \mathrm{~mm}, d=18 \mathrm{~mm}\) ?