#column-transformer

Question 1: Select all that apply

A column transformer applies different preprocessing to different columns of a table (for example scikit-learn's ColumnTransformer). Which statements about it are true? Select all that apply.

It can scale the numeric columns, one-hot encode the categorical ones and leave other columns unchanged, all in one step1
The columns of its output must come in the same order as in the original data2
Its output always has a different number of columns than its input3
On its own, without a model, it can be passed to cross-validation to get validation scores4

Timed test