 The challenge is this. Both Uma and Una get the same information from the relevant speakers. But in order to explain the difference in epistemic status between their awareness-episodes, the defender of knowledge iv needs to show that Una is aware of a distinctive mark X in virtue of which she can tell that there are five fruits hanging from the tree on the river-bank, but Uma isn’t aware of any such distinctive mark. But we could just stipulate that in Castor and Pollux, there is no property X such that Una is aware of X on the basis of Castor’s testimony, but Uma is not aware of X on the basis of Pollux’s testimony. This shows that we cannot clearly identify the distinctive mark X in every case of knowledge.