Answer:
Approaching the attractive woman; Desmond's racing heart
Step-by-step explanation:
Desmond sees an attractive woman whom he would like to meet, His heart start racing and his pupils dilate, as he start to approaching that woman.
In these conditions, approaching the attractive woman is the stressor because approaching the woman causes heart beat racing and pupil dilate, and Desmond's racing heart is the stress because it occurs in the response of stressor.