18. Cartographers have long struggled with the problem of having the spherical Earth to draw on a flat sheet of paper.
(A) having the spherical Earth to draw on a flat sheet of paper
(B) having a flat sheet of paper on which to draw the spherical Earth
(C) how can one draw the spherical Earth on a flat sheet of paper
(D) how they could use a flat sheet of paper to draw the spherical Earth
(E) how to draw the spherical Earth on a flat sheet of paper