Correct Answer: CThe correct code block returns a DataFrame where the column storeCategory from DataFrame storesDF is split at the underscore character into column storeValueCategory and column storeSizeCategory. The split function, combined with the col function, is used to split the values in the storeCategory column by the underscore character. The correct code is: storesDF.withColumn('storeValueCategory', split(col('storeCategory'), '_')[0]).withColumn('storeSizeCategory', split(col('storeCategory'), '_')[1]). Here, split(col('storeCategory'), '_') splits the values in the storeCategory column by the '_' character and returns an array of strings. Index [0] and [1] are used to select the first and second elements of the resulting array, which are then assigned to the new columns storeValueCategory and storeSizeCategory, respectively.