You are the management accountant for Brideshead Tyres and have identified a linear relationship between the total direct material cost and the quantity of rubber used in production. Provide answers to the following questions, including reasons to explain your answer.
(a) Is this cost a variable cost or a semi-variable cost?
(b) Is this cost a unit level cost or a batch level cost?
(c) Is the quantity of rubber a useful cost driver for cost management?