Assuming you have below code:

print$($df$.$groupby$(\text{'}$main$\_$category'$).$count$())$

Which of the following is correct? $$

Question $4$ options:

The result of this code after running will return the row count for each main categories.

it will just output the same value when the datafame $"$df$"$ has been processed with fillna.

It will return the row count for each non$-$NA main categories on one column.

It will not be working as it should be given a $"[]"$ in the groupby method.