Global population growth has put a strain on: A. The natural environment
B. The use of technology
C. Social stratification
D. Trade between countries

A. the natural environment

Explanation:

else everything has been improved or expanded

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."

mammals. mammals of the piedmont region live in several habitats such as wetlands, fields and forests. raccoons live across the state including the piedmont. they've adapted to environmental changes, including the loss of natural habitat.