A、Monday. B、Tuesday. C、Wednesday. D、Thursday. B文中开头提到周二国家统计局公布的数据显示，截至2015年末，中国大陆男性人口达到7．0414亿人，而女性人口则为6．7048亿人。故选B。

(16) According to figures released by China’s National Bureau of Statistics on Tuesday, the number of men in the Chinese mainland stands at 704. 14 million while the number of their counterparts is 670. 48 million by the end of 2015.
    For every 113.51 boys born there were 100 girls (the natural rate is 102 to 107 boys to every 100 girls), the data showed.
    Though still far beyond the natural rate, China’s sex ratio at birth plunged by 2. 37 from 115. 88 of last year, the biggest drop in the last seven years.
    (17)To balance the population, China further relaxed its more than three-decade-old family planning policy to allow all couples to have two children since the start of 2016.
China, like other countries with Asian cultures, held a historic preference for male offspring over female ones. Conservatives, especially old-fashioned clans in rural areas, regard boys as the only recognized heirs to carry on a family line.
    The family planning policy, which was introduced in the 1980s to encourage each couple to have just one child, has pushed the sex ratio at birth up to some degree.
    Some families prefer boys if they can only have one child, said Chen Jian, Vice President of China Society of Economic Reform, adding that the gap between sexes at birth will narrow as the two-child policy is implemented.
    (18) If the sex gap continues to exist, it will threaten the population ecology and sustainable economic and social development, said Chen.
    "The most noticeable impact is a marriage squeeze. Left-over men will find it more difficult to marry women", Chen added.
16. When were the figures released?
17. In order to balance the population, what did China do?
18. Which is NOT the influence of the existence of sex gap?