Question

which factor is likely to be of concern in a developed economy in the twenty - first century?
populations that are growing too quickly
higher unemployment among less - skilled workers
low gdp
a labor shortage in manufacturing industries

Explanation:

In developed economies, manufacturing often faces labor shortages due to skill mismatches or demographic shifts. High GDP (not low), slower population growth (not too quick), and lower unskilled unemployment (not higher) are typical. So "a labor shortage in manufacturing industries" is a key concern.

Answer:

a labor shortage in manufacturing industries