Guitar Inc uses the number music lessons provided as its measure of activity. During April, the company budgeted for 350 music lessons, but its actual level of activity was 345 music lessons. Salary expense is a mixed cost of $5,200 per month plus $45 per music lesson. Salary expense in the planning (static) budget is closest to: A. $20,725 B. $20,950 C. $5,200 D. $15,750