In an experiment comparing shampoo effects, how many factors are being considered?

In an experiment comparing shampoo effects, the number of factors considered typically refers to the variables that are being manipulated or controlled to observe their effects on the outcome. When only one factor is manipulated, such as the type of shampoo used (for example, brand A vs. brand B), this constitutes a single-factor experiment.

In this context, if the experiment focuses solely on how different shampoos affect a specific outcome (like hair shine or softness) without incorporating additional variables—like the amount of shampoo used, hair type, or washing frequency—then only one factor is being examined.

This design helps isolate the effects of the shampoo itself, making it easier to draw conclusions about its effectiveness. If there were multiple factors being adjusted or compared, such as brand, quantity, and application method, then the number of factors would increase. However, since the question indicates only a singular focus, the conclusion of one factor is correct.