Marigold Corp. spent $4800 to produce Product 89, which can be sold as is for $6000, or processed further incurring additional costs of $1800 and then be sold for $8400. Which amounts are relevant to the decision about Product 89?

a. $4800, $6000, $1800 and $8400

b. $4800, $6000, and $8400

c. $6000, $1800, and $8400

d. $4800, $6000, and $1800