Final answer:
Nepal and Bhutan have less arable land compared to other South Asian countries due to their mountainous terrain and environmental protection policies.
Step-by-step explanation:
Due to their location in the Himalayas, Nepal and Bhutan have less arable land than other South Asian countries. Nepal's best farmland is in the Terai lowlands, but the north is dominated by the mountainous terrain. The rapid population growth is causing deforestation and soil erosion, further reducing the arable land available. Bhutan, on the other hand, has opted to restrict tourism and maintain its environmental health, which impacts the availability of developable land and other resources.