A unit chooses to study abroad, provided that it is proficient in business and fluent in English or French. Xiao Hong was not selected. Which of the following explanations can be derived from the above? ['Xiao Hong is not only fluent in English, but also needs French to be more fluent than other candidates.', 'If Xiao Hong is proficient in business, then she is not fluent in English and French.', 'Xiaohong is proficient in business but not fluent in English.', 'Xiao Hong is proficient in business, but not fluent in French.']