Marginal costing values inventory at variable cost per unit only Steps:

• Identify all variable production costs from the given information: only direct labour $12,000 is specified as variable; factory expenses$4,080 are fixed and excluded.
• Confirm units for costing: production of 2,400 units (no opening inventory affects this).
• Note missing data: no direct materials or variable overhead costs provided, which are typically needed for full marginal cost.
• Conclude: without complete variable costs, marginal cost per unit cannot be calculated precisely.

Why A is correct:

• Not applicable; insufficient data to verify any option.

Why the others are wrong:

• B: Likely from mistakenly including fixed costs and dividing by units sold (2,000), approximating $8.
• C: Possibly from absorbing fixed costs over production units, yielding ~$6.70 but adjusted incorrectly.
• D: Could result from absorbing total costs over closing inventory units only, an invalid approach.

Final answer: Not enough information.