单选题 One of the difficulties in carrying out worldwide birth control is that ______.

A、 official attitudes to population and birth control vary from country to country
B、 different countries have different customs and practices on birth control
C、 decreasing birth rate may lead to unemployment in some countries
D、 in some countries people think that they enjoy the right to have as many children as they like

【正确答案】 A

【答案解析】[解析] 从文中第二段第四、五句In a highly industrialized society…A decreasing birthrate…unemployment…不难看出，在发达国家，出生率下降，人们会失业；而在其他国家，情况则恰恰相反。故选A。