The correct answer is D. All of the mentioned.
Merging is the process of combining two or more datasets into a single dataset. The datasets must have the same observations, but they can have different variables. The result of a merge is a dataset with all of the variables from the original datasets, plus any new variables that were created during the merge.
Data visualization is the process of representing data in a graphical or pictorial format. This can be done using a variety of tools, such as charts, graphs, and maps. Data visualization can be used to communicate data more effectively, to identify patterns and trends, and to make better decisions.
Subsetting is the process of selecting a subset of observations from a dataset. This can be done using a variety of criteria, such as the values of certain variables or the dates of the observations. The result of a subset is a new dataset that contains only the selected observations.
All of these are valid data analysis techniques. However, the statement “All of the mentioned” is incorrect because it implies that all of these techniques are always appropriate to use. In reality, the best technique to use depends on the specific data analysis problem that is being solved.