19) D

Percentage change of sales of Mirror from 1992 to 2018 = -80%
Sales of mirror in 2018 = 583190 ≈ 580,000
So sales have reduced by 80% from 1992 to 2018.
Let us say sales in 1992 were X.
X – 80%X = 580,000
80% of X = 0.8X

1X – 0.8X = 580,000
0.2X = 580,000
X = 580,000 ÷ 0.2 ≈ 2.9 m