Question

The decline in approximately 70% of the worlds bird species is particularly alarming to scientists because ____.​

a. ​this is the first time any bird species have been threatened with declining numbers

b. ​the cause is a non-human activity that scientists cannot determine.

c. ​only land birds are affected, while water birds seem to be maintaining normal population numbers

d. ​birds are excellent environmental indicators

e. ​bird watching now generates a significant portion of tourist dollars in some countries

Answer

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