A five-year-old child knows over six thousand words he or she has also learned more than one thousand rules of grammar. (单选题)
A.
A five-year-old child knows over six thousand words, he or she has also learned more than one thousand rules of grammar.
B.
A five-year-old child knows over six thousand words. He or she, has also learned more than one thousand rules of grammar.
C.
A five-year-old child knows over six thousand words. He, or she has also learned more than one thousand rules of grammar.
D.
A five-year-old child knows over six thousand words, and he or she has also learned more than one thousand rules of grammar.