Darcy is sitting at her desk in her office · one day when, without warning, her heart begins racing rapidly, she starts sweating profusely, and she is gripped with a terrifying fear that she is about to go crazy. she thinks she is having a heart attack. nothing she is doing seems to have caused such an episode. her symptoms most resemble
a. a phobic disorder
b. a panic attack
c. post-traumatic stress
d. a compulsion

b. a panic attack

Explanation:

According to the DSM-V, a panic attack refers to an episode in which the individual experiences intense fear and discomfort that reach a peak within a few minutes during which the individual experiences physical symptoms such as chest pain, heart palpitations, breathlessness, sometimes accompanied by the fear of losing control, going crazy or dying.

Darcy is sitting at her desk and unexpectedly her heart races, she starts sweating and she has a terrifying fear that she is about to go crazy.  She is experiencing the typical symptoms of a panic attack.

Note:

A phobic disorder refers to a fear of something specific, in this example Darcy doesn't really has an specific trigger for her symptoms (it happened without warning).

Post-traumatic stress is a disorder that includes episodes of intense fear but they are triggered by an stimulus related to an event that happened before and which caused a trauma in the individual. Again, the example tells us that this happened without warning and without any apparent cause.

A compulsion refers to a behavior an individual realizes to eliminate thoughts that cause him/her anxiety. In this example, Darcy is not having a behavior in order to reduce anxiety.

explanation:

may i ask what challenges?