Question

1. at the end of the twentieth century, ______ have been added to environmental thinking

a. global concerns
b. urban problems
c. water supply and pollution problems
d. human population growth
e. air pollution problems

Explanation:

The question is about environmental issues added to environmental thinking by the end of the 20th century. "Global concerns" (A) is the broadest and most overarching, as issues like water, air pollution, urban, and population growth are part of global environmental concerns.

Answer:

A. global concerns