To answer this question, we should deeply realize that under the background of the world financial crisis, China's export enterprises have improved the international competitiveness of their products and their export share has been expanding. At the same time, we should pay attention to distinguish between the expansion of export share and the substantial increase of investment here. This topic is essentially to examine the reasons for the growth of China's export share. The competitiveness of manufacturing industry is enhanced, the export products are increased, and the export share is correspondingly expanded. Item a meets the meaning of the question; The expansion of export share is different from the substantial increase of foreign investment, and B does not meet the meaning of the question; The appreciation of RMB is not conducive to exports, which is inconsistent with the meaning of the question; Item d is contrary to the requirements of the topic. Therefore, choose a in this question.