Bargain Booksellers sold 40,000 books in April and 65,000 books in December. Shipping costs for the two months were $150,000 and $200,000, respectively. Using these two months' data, the shipping cost function is best estimated as

(a)

($2.00 number of books sold) + $70,000

(b)

($0.50 number of books sold) + $167,500

(c)

($3.33 number of books sold)

(d)

($2.00 number of books sold) + $50,000

Showing work will be greatly appreciated, thanks