Normal, ordinary people who have occasional intrusive thoughts with bizarre, sexual, or aggressive content would not be considered to have ocd unless they find the thoughts unacceptable or even dangerous and also

I believe the answer is: c. become anxious about having further intrusive thoughts.

People who develop obsessive compulsive disorder tend to experience an extremely intense shock after being put in a stressful situation. The chance of ocd from occuring massively increased if that stressful situation is a close bet between life and death, and caused them to constantly experience sudden panic even after they already get out from the situation.