What factor may increase the risk of cold injuries in clients who smoke?

Heightened sensitivity to cold from nicotine is the correct choice because nicotine has several physiological effects that can influence the body’s response to cold temperatures. When smoking, the nicotine causes blood vessels to constrict, which reduces blood flow and can lead to an increased sensitivity to cold temperatures in the skin and extremities. This physiological response makes individuals who smoke more susceptible to cold injuries, as their bodies may not effectively maintain warmth in colder environments.

The other factors might contribute to overall health risks or behaviors associated with smoking but do not directly relate to the increased risk of cold injuries. For instance, improved circulation from smoking is misleading, as smoking typically results in blood vessel constriction rather than improved circulation. A compromised immune response due to smoking is more about susceptibility to infections rather than a direct connection to cold injuries. Similarly, while time spent outdoors may increase exposure to cold, it is not a specific factor linked to the heightened risk of cold injuries for smokers as is the biological effect of nicotine itself.