When was the “two-child” policy adopted in China?

Câu hỏi: Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.
For three decades, China operated the "one-child" policy of population control. This was abandoned in 2016 in favor of a two-child policy to boost the labor force. But average fertility rates keep falling, even as restrictions are lifted. In 2016, after the one-child policy was abandoned, there were 17.86 million births. This dropped to 17.2 million in 2017 and 15.2 million in 2018 – the third-lowest rate since the foundation of the People's Republic of China in 1949.
Much of China's astonishing economic growth of the past four decades has been fueled by a young labor force, but this too is in rapid decline, while the elderly population is dramatically increasing. In China in 2017, the ratio was six workers in the 20-64 age bracket supporting one senior citizen at least 65 years old. This will decline to 2.0 workers in 2039 and 1.6 in 2050. "No social security net, no family security and a pension crisis — this will evolve into a humanitarian catastrophe. As women live six to seven years longer than men on average [and are usually a few years younger than their husbands], they will be the main victims of population control," said Yi.
Clearly more needs to be done to encourage women to have more children. But couples in developed societies have fewer kids, largely because of expensive education costs and pressure on household incomes in the cities. Average fertility rates in Taiwan and Hong Kong from 2001 to 2018 were 1.14 and 1.07 respectively. "The best way to get more women to have more children is to make it easy and cheap for women to get good reliable childcare, and work," said George Magnus, a research associate at Oxford University's China Centre, and at SOAS.
We live in a grey world. For the first time last year, there were more people on Earth who were 65 and over than children under 5. Because of the sheer pace of aging, China appears doomed to get old before it gets rich. "Measured by the proportion of 65+ and the old age dependency ratio, China will age as much in the next 22 years as most Western economies have done in the last 60-70 years — and at far lower levels of income per head, and with a much less developed social security system," Magnus said. By 2040, China's income per head could be anywhere between 20,000 USD (18,000 Euro) and 40,000 USD per head depending on what happens to the economy and growth.
The key to easing the effects of a greying population in China is to raise the participation of older workers and women in the workforce. It also needs to look to immigration, currently at negligible levels in China. And key to all of this is productivity. "Higher productivity is the Holy Grail, but how to deliver it? Investment in new technologies should help," said Magnus.
When was the "two-child" policy adopted in China?
A. In 1986
B. In 2016
C. In 2017
D. In 2018