relvent cost and decision making

MCQ

A farmer grows potatoes for sale to wholesalers and to individual customers. The
farmer currently digs up the potatoes and sells them in 20 kg sacks. He is considering
a decision to make a change to this current approach. He thinks that washing the
potatoes and packaging them in 2 kg cartons might be more attractive to some of his
individual customers. Which of the following is relevant to his decision?

(i) the sales value of the dug potatoes
(ii) the cost per kg of growing the potatoes
(iii) the cost of washing and packaging the potatoes
(iv) the sales value of the washed and packaged potatoes

(A) (ii), (iii) and (iv) only
(B) (i), (ii) and (iii) only
(C) (i), (ii) and (iv) only
(D) (i), (iii) and (iv) only

The answer is D . but explain why ;(i), (iii) and (iv) are relevant and (ii) is not relevant ; ??

I want 300 words and give reasons for each sepreatly ;