Question $10$

Which of the following is not a valid expression to create a Pandas GroupBy object from the DataFrame shown below?

$1$ point

df$.$groupby$(\text{'}$class$\text{'},$ axis $=0)$

df$.$groupby$(\text{'}$vegetable$\text{'})$

grouped $=$ df$.$groupby$([\text{'}$class$\text{'},$ 'avg calories per unit'$])$

df$.$groupby$(\text{'}$class$\text{'})$