Information mismatch prevents calculation Steps:

• Identify the period: Income statement is for year ended 31 December 2017.
• Review data: All provided figures (receivables, provision, sales) are dated 1 January 2018 or "during the year" (implying 2018).
• Determine requirement: Need closing receivables at 31 December 2017 and prior provision to compute 4% provision adjustment for 2017.
• Conclude: No 2017-specific data given for receivables balance or sales to calculate the provision expense or income.

Why D is correct:
Not applicable; insufficient data for any option.

Why the others are wrong:

• A, B, C: All require 2017 closing receivables (opening + 2017 sales - collections), which are absent.

Not enough information.
Final answer: Not enough information.