'What' clauses can and 'which' cannot: A Romanian puzzle

A previously unnoticed puzzle is presented concerning the distribution of wh-determiners in free relative clauses in Romanian: while care 'which' + NP can never introduce free relative clauses, ce 'what' + NP does so productively, as do all other wh-words. New evidence is provided showing that care 'which' + NP in interrogative clauses in Romanian exhibits strong discourse-anaphoric requirements, unlike ce 'what' + NP. This feature of care 'which' + NP is suggested to be responsible for the puzzle by triggering a clash with the basic set-denoting function of a free relative clause, along the lines of what is observed in light-headed relative clauses.