The independent variable is the temperature.
The study aims to assess how the temperature level affects another variable, that, in turn, will be the dependent variable: the mood of the participants. The aim of the study is to conclude whether it is possible or not to infer causality between those two, in other words, to see whether different levels of temperature (<em>the cause</em>), trigger the emergence of a certain type of mood <em>(the effect).</em>
I think the answer is B but I could be wrong
They are lacking real human interaction. This can cause an increase in anxiety.
Answer: Selection bias
Explanation:
Selection bias is defined as the process in which individual or group of individual are analyzed for selection process by lacking randomization property .This process displays that selected sample of individuals is not similar representative of major interest population.
According to the question,the systematic difference that occurs in selected group for experiment as per their last name is displaying that selected group does not represent interest population that is causing systematic error.Thus, this situation describes about selection biasing.