Final answer:
Right-clicking a column header in the Query Editor provides options like 'Remove', 'Change Type', and 'Duplicate Column', but not 'Count Rows', which is a general data analysis feature.
Step-by-step explanation:
When you right-click a column header in the Query Editor window, three transformations that are commonly available include: Remove, Change Type, and Duplicate Column. 'Remove' will delete the selected column from your table. 'Change Type' allows you to convert the data type of the selected column, for example from text to number or from number to date. 'Duplicate Column' creates a copy of the selected column which can be useful for data manipulation without altering the original data. 'Count Rows' is not typically a transformation option associated directly with a column header right-click menu; it is more often found in general menu options for analyzing data sets rather than column-specific transformations.