Which statement best describes an impact of modern technology on standards of living in developing nations? -vaccines eliminate dangerous diseases, but their effectiveness declines over time.-computers and machines improve productivity, but reduce the need for human workers.-genetic engineering increases food output, but equitable distribution remains a problem.-biotechnology provides medicine for previously incurable diseases, but reduces life expectancy.

Among the options given on the question the correct answer is option B.

Computer and machines improve productivity, but reduce the need for human workers.

Explanation: In the developing nations, modern day technology has huge impact. It's not far away when the developing nation has  been introduced with the modern day technology in greater aspect.

Computers and machinery are used for improving productivity of a developing nation and it has become fruitful to them to use computer and machinery. The use of these technology also reduce the cost of labor for the production. Because the machine can do work instead of a human even more perfectly and rapidly.

So in many cases, people are loosing their job as there is no need of much human workers. Because a machine can work instead of human and multiple machine can be operated by one human.

So, using the computers and machine in the developing country causing unemployment in some cases as by using these technology the need for human workers is reducing.

the qing dynasty placed strict limits on foreign merchants' ability to trade in china.

uncle sam would be tossing and turning in his grave : *)