What is a question about this article? If the question is unanswerable, say "unanswerable".

Although most aspirated obstruents in the world's language are stops and affricates, aspirated fricatives such as [s], [f] or [] have been documented in Korean, in a few Tibeto-Burman languages, in some Oto-Manguean languages, and in the Siouan language Ofo. Some languages, such as Choni Tibetan, have up to four contrastive aspirated fricatives [s] [], [] and [x].

Choni Tibetan has how many unaspirated fricatives?
unanswerable