Which would be the MOST likely concern after traversing frozen ground to reach a drafting site?

The concern regarding thawing due to an increase in air temperature is particularly relevant in the context of traversing frozen ground to reach a drafting site. As temperatures rise, the frozen ground may begin to thaw unevenly, leading to potentially unstable conditions. The meltwater can create soft spots or muddy areas that can pose a risk of slipping or bogging down the vehicle, which impacts safety and operational efficiency.

Furthermore, as the ground transitions from frozen to thawed, the changes in traction and support beneath the vehicle can create challenges for successful drafting operations. Understanding this concern is critical for maintaining operational safety and ensuring that all personnel can navigate effectively in changing weather conditions.

The other options, while they may present concerns in specific situations, do not address the most immediate risk associated with navigating through frozen terrain. For instance, while ice buildup on parts and the inability to chock wheels can be problematic, they are not as directly related to the risks posed by changing terrain conditions as thawing would be.