Final answer:
Shawnda is best described as using a biophysiological measure of weather-related stress by analyzing salivary cortisol. This method aligns with response-based definitions of stress, emphasizing the physiological mechanisms involving the HPA axis's release of cortisol.
Step-by-step explanation:
In her study of psychological stress related to weather extremes, Shawnda's measurement of salivary cortisol levels can be best described as a biophysiological measure of weather-related stress. This approach falls within a response-based definition of stress, which conceptualizes the phenomenon in terms of the body's physiological reactions to demands, as characterized by Hans Selye. Salivary cortisol, known as a stress hormone, is part of the physiological mechanisms of stress involving the hypothalamic-pituitary-adrenal (HPA) axis, which activates in response to stress by releasing cortisol - a critical component of the body's fight-or-flight response.