Final answer:
The purchasing manager is most likely responsible for an unfavorable materials price variance, as this role involves negotiating material costs.
Step-by-step explanation:
An unfavorable materials price variance indicates that the actual cost of materials was higher than the budgeted or standard cost. When considering who is responsible for such a variance, it's important to consider which roles in a company are involved with the price and acquisition of materials. In this situation, the most likely individual responsible for the variance is the purchasing manager. This person is typically in charge of negotiating prices and terms with suppliers, and their actions directly influence the cost of materials procured for production.
While other roles contribute to the company's financial and operational well-being, the actions of the production supervisor, corporate attorney, personnel director, internal audit manager, and supervisor of the accounting department are less directly related to purchasing decisions that would cause an unfavorable price variance.