Ratios of D-meson production cross sections per unit of rapidity at midrapidity ($|y| < 0.5$) to those measured by LHCb in three rapidity intervals: $2 < y < 2.5$ (top-left panel), $3 < y < 3.5$ (top-right panel), and $4 < y < 4.5$ (bottom-left panel), as a function of $\pt$. Statistical (systematic) uncertainties are reported as vertical bars (boxes).