Answer: D. Linguistic flexibility
Explanation: A. Bilingualism is where a person can speak two languages.
B. Code-switching is where a person speaks two languages in the same sentence - "Kylie, ou est le bread? I forgot to de le ranger, but now I can't find it." that was English and French.
C. Language acquisition is where a child learns language through interaction.
D. Linguistic flexibility is where we emphasize a broad range of language practices within classroom spaces, characterized by hybridity and variation.
I hope this helps. if I'm wrong then I do apologize.