Three Major Studies That Compared Grammatical Development in Bilinguals to Monolinguals

Three major studies that compared grammatical development in bilinguals to monolinguals indicated that:

A) bilinguals develop grammatical knowledge in the same process and timeframe as monolinguals.
B) bilinguals have difficulty acquiring grammatical knowledge.
C) bilinguals mix languages and frequently produce errors.
D) monolinguals are slower than bilinguals to acquire proficient use of grammar.