At zero direct labor hours in a flexible budget graph, the total budgeted cost line intersects the vertical axis at $30,000. At 10,000 direct labor hours, a horizontal line drawn from the total budgeted cost line intersects the vertical axis at $90,000. Fixed and variable costs may be expressed as:

(a) $30,000 fixed plus $6 per direct labor hour variable.

(b) $30,000 fixed plus $9 per direct labor hour variable.

(c) $60,000 fixed plus $3 per direct labor hour variable.

(d) $60,000 fixed plus $6 per direct labor hour variable.