The correct answer is A.
<u>The dependent variable is:</u><u> how long students worked on the math problem.</u> Secondly, the goal of the study is to assess whether an explanatory variable (the confort of chairs) does have a causal effect on the lenght of math study or not.
As it is described in the question, the explanatory variable is a binary one: it takes value equal to 1 for the group seated in padded, comfortable chairs, and value 0 for the individuals in the group with standard chairs. Therefore, the study can be understood as the assesment on the validity of a treatment, on its capacity to make a difference on the dependent variable.
More or fewer but just know that 2 and 3 are out
One reason is for supplies like wood. Another reason is for space for farms. The last reason is because of growing cities.
Defense mechanisms are built-in mental processes that serve to function individuals during stressful situations or from stressful emotions.
