You have the following known facts: Smoking causes accumulat…

You have the following known facts: Smoking causes accumulation of materials in the lungs, thereby decreasing oxygen-absorbing capability of the lungs. Long-term smoking causes more accumulation of materials in the lungs. Decreased lung capacity increases the workload of the heart. Which of the following hypotheses can you make from these observations?

I notice that all the students in my class seem very drowsy…

I notice that all the students in my class seem very drowsy 45 minutes into my class period. Knowing that it could not possibly be my lecture putting them to sleep, I consider other factors such as the fact that my class is at 5 p.m. and the sun is usually setting at that time of the day, which I think may make people drowsy. What type of evidence am I collecting in making this observation?