To return a DataFrame with a column named divisionDistinct that contains the approximate number of distinct values in the column division from storesDF, the correct code block is storesDF.agg(approx_count_distinct(col('division')).alias('divisionDistinct')). This uses the agg function to perform an aggregation on the entire DataFrame, and approx_count_distinct to compute the approximate count of distinct values, with alias used to rename the resulting column.