In Pandas, which method is used to calculate the mode of a numerical column in a DataFrame?

The correct answer is B. mode().

The mode is the most frequent value in a set of data. It is calculated by finding the value that appears the most times in the data.

The sum() method calculates the sum of all the values in a column.

The median is the middle value in a sorted set of data.

The sum() method is not used to calculate the mode of a numerical column in a DataFrame.