Consider the following relational schema for an online programming platform: Users User ID Username Password Rank Questions Question ID Question title difficulty level description date posted Submissions User ID Question ID solution_status points date Write appropriate SQL queries for the questions below. For each question write a single query: A. Retrieve the question id, title and posting date of all questions from highest to lowest posting date [3] B. Retrieve the user id, rank, submitted question id and points of all submissions that have received the highest points [4] C. Retrieve the total total number of questions at each difficulty level. The query should show difficulty level and total number of questions [3]