In a data engineering project, you are tasked with transforming a large DataFrame 'df' with the schema (date: string, category: string, value: double) from a long format to a wide format. The wide format should have each category ('electronics', 'groceries', 'clothing') as its own column, with the sum of 'value' for each category. The solution must be optimized for performance to handle large datasets efficiently and ensure data accuracy. Additionally, the solution should minimize resource usage to keep costs low. Which of the following Spark SQL queries best accomplishes this task? Choose the best option. | Databricks Certified Data Engineer - Associate Quiz