To calculate the total of all salaries in the accounting department, you need to use the SUM function.

Option A (MAX) returns the highest value in a set of values.

Option B (MIN) returns the lowest value in a set of values.

Option C (SUM) is the correct option. It returns the sum of all values in a set of values.

Option D (COUNT) returns the number of values in a set of values.

Option E (TOTAL) is not a valid function in SQL.

Option F (LARGEST) is not a valid function in SQL.

Therefore, the answer is: C. SUM.