According to the college undergraduate stress scale, is rated as more stressful than is flunking a class.

The answer is flunking a class. Flunking a class during college years is the most stressful item in the College Undergraduate Stress Scale (CUSS). Flunking a class means failing it, which results to more stress, it will make you take it again, but it depends on that subject’s availability. You’re chances of graduating early may be hindered because of a flunked class. There is nothing more stressful than flunking a class.  

you did not give any options thus this is the best answer i can give to you with this little information you have given

> they are both natural and not man made

> they can be tracked and predicted by the right tools

-love shrooms