If an actual manufacturing overhead costs is $485000 and actual total quantity of cost allocation base is 4500 labour hours, then overhead rate would be

The correct answer is $\boxed{\text{A) 109.87}}$.

The overhead rate is calculated by dividing the actual manufacturing overhead costs by the actual total quantity of the cost allocation base. In this case, the actual manufacturing overhead costs are $485,000 and the actual total quantity of the cost allocation base is 4500 labor hours. Therefore, the overhead rate is $485,000 / 4500 = $109.87 per labor hour.

Option B is incorrect because it is the actual manufacturing overhead costs, not the overhead rate.

Option C is incorrect because it is the overhead rate rounded to the nearest cent.

Option D is incorrect because it is the overhead rate rounded down to the nearest dollar.