Question 6.

It’s easy to forget that most of the world’s languages are still transmitted orally with no widely established written form. While speech communities are increasingly involved in projects to protect their languages - in print, on air and online - orality is fragile and contributes to linguistic vulnerability. But indigenous languages are about much more than unusual words and intriguing grammar: They function as vehicles for the transmission of cultural traditions, environmental understandings and knowledge about medicinal plants, all at risk when elders die and livelihoods are disrupted.

From the underlined portions of the above excerpt, we can infer options A, B, and C.

The first paragraph does mention that indigenous languages have unusual words and intriguing grammar. But it has not been mentioned as a factor that makes their documentation challenging. Hence, Option D is the answer.