Studies on Whether and When Bilinguals Acquire Phonological Differentiation Indicate

Studies on whether and when bilinguals acquire phonological differentiation indicate that:

A) further research is required to get accurate results.
B) this occurs between 1-½ years and two years of age.
C) Spanish and English bilingual children acquire these skills at age three.
D) adults can clearly identify bilingual children's language through speech production when they are two years old.