Final answer:
Dave is exhibiting the 'Denial and isolation' stage of Elizabeth Kübler-Ross's five-stage model of grief after being informed of his advanced cancer diagnosis.
Step-by-step explanation:
When Dave was told by his doctor that he was in the advanced stages of cancer and he immediately questioned the report and sought a second opinion from another doctor, Dave is exhibiting the reaction to impending death known as Denial and isolation. This is according to Elizabeth Kübler-Ross's five-stage model of grief, which begins with denial. In this stage, individuals tend to not want to believe the reality of their situation, often seeking other explanations or refusing to accept the diagnosis.
The five stages of grief according to Kübler-Ross are: denial, anger, bargaining, depression, and acceptance. These stages are part of a framework to help us understand the emotional and psychological responses to grief and significant life-altering situations. It is also important to note that these stages are not necessarily experienced in a sequential order and not everyone goes through all the stages.