installment sales for 2018 is $600,000 and cost of goods sold $300,000 while the installment sales in 2019 is $1,000,000 and cost of goods sold $800,000,cash collection from 2018 sales was $400,000 in 2018 and $200,000 in 2019, cash collection from 2019 sales was $500,000 in 2019 and $500,000 in 2020, using installment sales method compute gross profit realized in 2018?

a. $300,000.

b. $40,000.

c. $400,000.

d. $200,000.