A. Providing for the needs of its aging population
Explanation:
The population pyramid shows that the group of people with the highest population as at year 2000, are people of the ages between 40 - 44, and 35 - 39. These group of people are arguably the active and working class people of China.
By 2029, that's about 29 years to come, most of these groups of people who be aged already and retired from active service.
Therefore, China would be faced with the demographic challenge of providing for the needs of its aging population, beginning from 2029.
