Prime costs include direct materials, labor, and expenses

Steps:

• Recall prime cost definition: direct costs directly traceable to production, like materials and labor.
• Identify direct expenses: costs like transport of raw materials into the factory.
• Classify each option: check if it's directly linked to making the product.
• Select the one fitting direct material acquisition.

Why A is correct:

• Carriage inwards is a direct expense added to material costs, per prime cost formula (direct materials + direct labor + direct expenses).

Why the others are wrong:

• B: Carriage outwards is a selling/distribution overhead, not direct to production.
• C: Factory rent is indirect factory overhead, absorbed across all units.
• D: Factory supervisor's salary is indirect labor overhead, not traceable to specific products.

Final answer: A