Divisional management stated that a recent gross margin increase was due to increased efficiency in manufacturing operations. Which of the following audit procedures would be most relevant to that assertion?

(a) Obtain a physical count of inventory.

(b) Select a sample of products, then compare costs-per-unit this year to those of last year, test cost buildups, and analyse standard cost variances.

(c) Take a physical inventory of equipment to determine if there were significant changes.

(d) Select a sample of finished goods inventory and trace raw materials cost back to purchase prices in order to determine the accuracy of the recorded raw materials price.