Photospheric abundance determinations of C+N+O (blue) and Si (red) for each star as a fraction of solar compared to the adopted host galaxy metallicity, Z, from Table 2. Data points indicate whether the host galaxy metallicity Z was determined from nebular emission (circles) or through spectroscopic analysis of supergiants (squares). The vertical dotted line represents equality between our abundance determination and the solar value scaled to the adopted metallicity of the host galaxy. The troublesome runs of A11 and B11 are highlighted in grey.