单选题 The passage suggests that all research has proven that which of the following is true about the phenomenon of synesthesia?

• (A) The lack of synesthetic color differences tends to hinder synesthetics in the same tasks where the presence of real color differences assists nonsynesthetes.
• (B) The presence of real color differences tends to assist nonsynesthetes in the same tasks where the lack of synesthetic color differences assists synesthetes.
• (C) The presence of synesthetic color differences tends to assist synesthetics in the same tasks where the presence of real color differences hinders nonsynesthetes.
• (D) The lack of synesthetic color differences tends to hinder nonsynesthetes in the same tasks where the presence of real color differences assists synesthetes.
• (E) The presence of real color differences tends to assist synesthetes in the same tasks where the lack of synesthetic color differences hinders nonsynesthetes.