C) 38,000
Explanation:
The estimated warranty liability for 2017:
= [2016 sales x (first + second year warranty costs)] + [2017 sales x (first + second year warranty costs)] - (warranty expenses for 2016 and 2017)
= [$600,000 x (2% + 5%)] + [$800,000 x (2% + 5%)] - ($20,000 + $40,000)
= $42,000 + $56,000 - $60,000 = $38,000