Ruben wants to determine if listening to different types of music will affect a person's pulse. His hypothesis states that if people listen to music, their pulse will increase more than if they listen to other types of sound, such as white noise. Ruben tests his mother, sister, and cousin. He takes each participant's pulse before, during, and after listening to 30 minutes of music, and then repeats the process with 30 minutes of white noise. From the data collected, he concludes that music raises a person's pulse the most. Which characteristic of science is missing from this experiment?

The question is not testable because a person's pulse is affected by other factors.
The phenomenon is not observable because a person's pulse is not measurable.
The experiment is not replicable because the testing conditions are not included.
The results are unreliable because the testing sample of the experiment is too small.