In Folland's Advanced Calculus, when discussing Stokes' Theorem, the surfaces are oriented by a choice of normal (either inwards or outwards). Visually, it's easy to see which direction is inwards and outwards, especially for simple shapes such as cylinders. But I have not seen a rigorous definition of
In Spivak's Calculus on Manifolds, we orient a manifold by a coordinate system that is either orientation preserving (i.e. preserves the standard orientation $e_1, \ldots, e_n$), or orientation reversing.
Must surfaces oriented by outward pointing normals (in the Folland sense) be A) orientation preserving (in the Spivak sense), or B) orientation reversing, or C) is there is no relationship at all, and depends on the manifold. Why?