The correct answer is A. $803.571 per labour hour.
The budgeted manufacturing overhead rate is calculated by dividing the budgeted annual manufacturing indirect cost by the cost allocation base. In this case, the budgeted annual manufacturing indirect cost is $2250000 and the cost allocation base is 2800 labour hours. Therefore, the budgeted manufacturing overhead rate is $2250000 / 2800 labour hours = $803.571 per labour hour.
Option B is incorrect because it is the budgeted annual manufacturing indirect cost per labour hour, not the budgeted manufacturing overhead rate.
Option C is incorrect because it is the budgeted annual manufacturing indirect cost per labour hour plus 10%, not the budgeted manufacturing overhead rate.
Option D is incorrect because it is the budgeted annual manufacturing indirect cost per labour hour minus 5%, not the budgeted manufacturing overhead rate.