Inventory undervaluation from omission and improper costing Steps:

• Goods costing $100 omitted, understating inventory by$100.
• Goods costing $70 included at$20 (NRV) instead of cost, understating by $50 ($70 - $20).
• Total understatement: $100 +$50 = $150.
• Effect: Assets and profit understated by $150 on 31 December 2019 statements.

Why D is correct:

• D reflects total understatement of $150, per inventory valuation rule at cost (or lower of cost/NRV, but error assumes cost basis here).

Why the others are wrong:

• A: Misinterprets second error as overstatement ($70 cost vs.$20 NRV nets wrong direction).
• B: Considers only second error's $50 difference, ignoring omission.
• C: Adds omission to NRV value ($100 +$20 = $120), using wrong basis.

Final answer: D