I tend to agree with the other two posts.
Since there is no Insulation type given, this could be anything from TW [60 degree C], to THHN [90 degree C].
Since we can use Conductors with THHN Insulation and rate them at 60 degrees C for wet locations, or 90 degrees C for dry locations [for ampacity adjustments], this would exclude (c) and (d).
Since we are to use the 60 degree ampacity column in 310-16 for conductors sized #14 through #1, this would eliminate (a).
By default, the only remaining answer would be (b).
Scott SET
