For 2017, P Co. estimated its two-year equipment warranty costs based on $23 per unit sold in 2017. Experience during 2018 indicated that the estimate should have been based on $25 per unit. The effect of this $2 difference from the estimate is reported:

In 2018 income from continuing operations.

As an accounting change, net of tax, below 2018 income from continuing operations.

As an accounting change requiring 2017 financial statements to be restated.

As a correction of an error requiring 2017 financial statements to be restated.