EUV images of the sunspot indicated by the rectangle in Figure 1(a), at (a) 1700 Å, (b) He II 304 Å, and (c) Fe IX 171 Å, acquired by the AIA on 2015 December 16, and (d) a line-of-sight magnetogram obtained by HMI. The overlaid contours indicate the radio brightness temperature at λ = 3 mm observed by ALMA at the same brightness temperatures as in Figure 1(d).