Which factor is likely to have contributed to the rise in the Rocky Mountain mule deer population in the early 20th century?

The rise in the Rocky Mountain mule deer population in the early 20th century can be largely attributed to human intervention and land protection. During this period, significant efforts were made to conserve wildlife and their habitats. Establishing national parks and wildlife reserves helped provide safe environments for deer populations to thrive without the pressure of hunting and habitat destruction. These protective measures allowed mule deer populations to recover, as they were given a chance to repopulate and spread within these safeguarded areas.

The focus on conservation also included initiatives to implement wildlife management practices, which further contributed to the stability and growth of the mule deer population. These actions demonstrate the positive impact that human intervention can have on wildlife populations, particularly when it involves protecting their natural habitats from external pressures.