A company uses functions to model the costs to produce and market a product.

The cost, in thousands of dollars, to produce x units of the product is modeled by function j:
j(x) = 17 + 0.05x.

The cost, in thousands of dollars, to market x units of the product is modeled by function k:
k(x) = 4 + 0.03x.

Which function correctly represents the total cost, in thousands of dollars, to produce and market x units of the product?

A.
c(x) = 21 + 0.08x2
B.
c(x) = 13 + 0.02x2
C.
c(x) = 13 + 0.02x
D.
c(x) = 21 + 0.08x