submillimeter ALMA data (Fig.\[Evectors\]) show an arc-like distribution of the polarization vectors in region A (see their position angles) which deviate from the spherical symmetric pattern around the central star. This implies that radiative grain alignment (or alignment with radiation anisotropy) is not the dominant mechanism for grain alignment here. It is possible that the polarization in the inner region of the nebula (area B, see Fig.\[Evectors\]) is due to the radiation field, since many of the $\overrightarrow{E}$-vectors in this area could be related to a spherical symmetric geometry. However, this pattern is incomplete as it is not seen in the southern part of region B, and the mean percentage polarization is relatively low ( $\simeq$1%), both at 230 GHz (CARMA data) and at 345 GHz (ALMA data). So we disregard radiative alignment as the main polarization process operating in OH 231.8+4.2. One would expect higher percentage at this location, or in other words, a more efficient alignment of the dust grains. Detailed modelling, involving different radiation field intensities, observing wavelengths, and dust grain sizes (@Ohashi2018 [@Tazaki2017]), would be needed to assess if and in which conditions this alignment process would be viable.\
The second polarization mechanism unrelated to magnetic 