Concept:Fruits used for jam and marmalade must have the right ripeness for good flavour, pectin, and setting quality.Explanation:Fruits should be just ripe because they contain enough pectin and acid to help the jam set properly.Under-ripe fruits are hard and low in flavour, while overripe fruits have too little pectin and may not set well.Bruised or fibrous fruits are unsuitable for good-quality jam.Answer:D. just ripe