Or (c) lower the price to the market clearing price point and your clothes will be gone.
Market clearing prices can be negative i.e. you have to pay someone to "buy" them. This regularly happens in commodities markets. In agriculture, for example, negative market clearing prices is why a lot of food ends up in a landfill instead of on store shelves.
You're assuming there is such a price! Charity shops throw out the majority of clothes they are given: some things just will never sell.[1]
[1] https://theclothingbank.org.uk/what-happens-to-the-clothes-y...