Question

why is it not possible for an outsider to fully interpret a winter count?
the glyphs were used as a secret code.
the glyphs do not actually mean anything.
it requires the oral history associated with each glyph.

Explanation:

Winter counts are visual records by some Native American tribes. Glyphs in them are not just standalone symbols. They are connected to the tribe's oral history. An outsider lacks the deep - rooted oral traditions that give full meaning to each glyph. The first option about secret code is incorrect as it's more about cultural context than secrecy. The second option is wrong because glyphs do have meaning within the tribe's context.

Answer:

It requires the oral history associated with each glyph.