a
1800
b
1940
c
1970
d
2000
Answer and Detail: The correct answer is: 1940.
Detail: The Copernicus Climate Change Service (C3S) began keeping records in 1940, which provide essential data for monitoring climate trends and impacts.
Detail: The Copernicus Climate Change Service (C3S) began keeping records in 1940, which provide essential data for monitoring climate trends and impacts.