Bullocks are moderately built animals that need frequent short breaks, so they work best on a 2-hours-work, 1-hour-rest cycle repeated through the day (II). Buffaloes are heat-sensitive because of their dark skin and limited sweating ability, so they do best with a long midday break: 4 hours of work in the cool morning, 7 hours of rest through the heat of the afternoon, then 4 more hours in the evening (III).
Camels, being adapted to harsh environments, can sustain longer stretches of 3 hours' work with shorter rests in between (IV), while donkeys work in short 1-hour bursts adding up to about 6 hours, with matching 1-hour rests (I).
Matching Bullock-II, Buffalo-III, Camel-IV, Donkey-I gives option 2.