Answer:
A. Randomized experiment.
Seee explanation below.
Step-by-step explanation:
Previous concepts
In a Randomized experiment the results can be use to establish causal inferences about means of control. and present two important characteristics:
a) "the independent or explanatory variable is controlled by direct manipulation.
b) "All other sources of variability are controlled by chance".
An observational study is an empirical but is nonexperimental investigation in order to see the effects caused by an specific treatment.
Solution to the problem
For this case we want to determine the effect of adhesive brands on the bonding of veneer to cabinets.
The experiment is conducted with 6 different groups defined with different adhesive and all the groups are the same except by the type of brand for the adhesive used.
So on this case we see that the variable of interest is controlled with direct manipulation with the creation of the 6 groups. And we have that all the the others sources of variability are controlled by chance since all the groups are identical except by the brand type.
So for this case the correct answer would be:
A. Randomized experiment.
