Which of the Following Children Would You Consider Assessing the Child's

Which of the following children would you consider assessing the child's ability to produce tones?

A) Giang (4;3 years) : multilingual and learning to speak English and Vietnamese.
B) Josef (4;5 years) : multilingual and learning to speak English and German.
C) Ryan (4;3 years) : monolingual and learning to speak English.
D) Abdul (4;11 years) : multilingual and learning to speak Arabic and English.