問題文
A cleaning step must keep only the rows that have at least three non-null values among five named columns. Which parameter of the drop method on the na property expresses that?
選択肢
- The how parameter set to any together with a subset of three columns, which requires three values to be present.
- The threshold parameter set to three, which overrides the any-or-all behavior.
- The subset parameter with three of the five column names, which limits the check to those columns.
- The how parameter value set to all, which keeps a row unless every value is null.