According to the actual definition of A horizon in the Soil Survey manual (2017), they are C horizons even with some organic matter is present. See below the last sentence of the definition below

Definition of the Soil Survey manual (2017):

A horizons are mineral horizons that formed at the soil surface or below an O horizon.
They exhibit obliteration of all or much of any original rock structure and show one or both of the following:
1 An accumulation of humified organic matter closely mixed with the mineral fraction and not dominated by properties characteristic of V, E, or B horizons; and/or
2. Properties resulting from cultivation, pasturing, or similar kinds of disturbance.

If a surface horizon has properties of both A and E horizons but the feature emphasized is an accumulation of humified organic matter, it is designated as an A horizon. Recent alluvial or eolian deposits that retain most of the original rock structure are not considered to be A horizons unless they are cultivated.

Jerome Juilleret