How can you add a new column to an existing DataFrame in pandas?Use the assign$()$ method, e$.$g$.,$ df$.$assign$($new$\_$column $=$ expression$)$Use the insert$()$ method, e$.$g$.,$ df$.$insert$($position$,$ new$\_$column, expression$)$Use the bracket notation, e$.$g$.,$ df$[$new$\_$column$]=$ expressionAll of these answers are correct