How does the health of polar bears indicate the health of the environment

How it indicates the health of the environment is when the less food, shelter, and mates cause population reduction and if nothing done to stop (or reduce) the amount of thing being taken away they could go extincted.

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space exploration has led to the development and technological improvement of many everyday items. (if this answer is wrong i will find the right answer) : )

answer; 4 electrons;