DataFrame.select() is classified as a transformation. Transformations in the context of DataFrames are operations that are lazily evaluated and result in a new DataFrame, without triggering the execution of the operations on the data. DataFrame.select() fits this definition as it allows selecting specific columns from the DataFrame, creating a new DataFrame with these columns. The other options listed, such as DataFrame.count(), DataFrame.show(), DataFrame.first(), and DataFrame.collect(), are actions that trigger the execution of transformations and return results, and thus are not considered transformations.