What is China's estimated population size?

China's estimated population size is approximately 1.5 billion, making it the most populous country in the world. According to the most recent statistics, the population has been reported to have crossed the 1.4 billion mark, with estimates placing it around 1.5 billion in multiple demographic surveys. This significant population growth is attributed to several factors, including historical events, urbanization, and government policies, including the one-child policy which was implemented in the late 20th century and its impact on population dynamics.

The answer fits the context of demographic studies showing that China's population has steadily increased over the decades. The figure of 1.3 billion is outdated, and while 1 billion and 1.1 billion are significantly lower than the current estimates, they do not reflect the dramatic growth China has experienced. Thus, based on the latest available data, the choice of 1.5 billion aligns accurately with the current understanding of China's population size.