Left: continuum- and sky-subtracted Hα image taken from Knapen (1998). The H II regions identified by Knapen (1998) are indicated with black circles. Note that the sizes of the circles do not represent the physical sizes of the H II regions. Right: ALMA ¹²CO (1–0) image (contours) overlaid on the Hα image. The contour levels are in steps of 3, 10, 20, 50, and 100 σ, where 1σ = 0.3 Jy beam⁻¹ km s⁻¹ (same as Figure 1).