Western Governors University (WGU) ITEC2117 D427 Data Management - Applications Pre-Assessment Practice

The SQL command that effectively counts how many students have each grade is structured as "SELECT grade, COUNT(*) FROM student_grades GROUP BY grade." This command is correct because it retrieves each unique grade from the `student_grades` table and counts the occurrences of each grade. The use of the GROUP BY clause is essential in this context, as it groups the result set by the specified grade, allowing the COUNT function to provide a total for each group.

A crucial part of this command is the SELECT statement, which specifies that both the grade and the count of students should be included in the output. By grouping the results by grade, the database engine processes the table and aggregates the data, producing a summarized view that indicates how many students have received each grade.

The other options do not fulfill all the requirements needed to achieve the desired outcome. For instance, the first option simply tries to count the total number of rows in the `student_grades` table without distinguishing between different grades. The second option attempts to use the COUNT function but lacks the necessary SELECT statement and GROUP BY clause. The last option incorrectly places GROUP BY after the FROM clause rather than within a proper SELECT statement, resulting in a syntactical error. Thus, option C is the only