Why did pastoralists sometimes have to reduce their herd size under colonial rule?

Correct answer: Because grazing areas and resources had reduced

Colonial policies reduced the land available for grazing. Forest laws, reserved forests, cultivation, and restrictions on movement meant that pastoralists could not freely use earlier grazing grounds. When fodder and water become limited, a large herd becomes difficult to feed and manage. Reducing the herd can therefore be a practical response to shrinking resources, not a sign that animals have lost all value.

Option A is correct because it directly connects fewer grazing areas and resources with the need to keep fewer animals. Options B, C, and D do not explain the historical situation: animal prices did not become zero, forests were not all opened, and animals did not leave for the sea. The key idea is that colonial control over land made pastoral livelihoods harder.