shout out to @graceseyoum800-1-1 for teaching me how to embed on here (3(/p)

Hi this is late but I hope it's helpful. From my understanding this is how I looked at the different hypotheses from your example:

A = taking Dramamine and B = having symptoms of sickness

1. Taking Dramamine causes symptoms of sickness - this is unlikely because Dramamine is meant to mitigate symptoms of motion sickness

2. Symptoms of sickness cause someone to take Dramamine - this one is likely as it could be that because someone is feeling motion sick, it would cause them to take Dramamine to manage symptoms but if B did not precede A, then B did not cause A.

3. A third factor causes someone to take Dramamine as well as exhibit symptoms of sickness - this one is also likely to me as the "C" factor could be being on a cruise ship, since the movement of the ship could result in both people preemptively taking dramamine and exhibiting symptoms of sickness

4. No causal relationship - I also do not think it's this one

That was my take on it!