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On average, how long does it take for scientists to completely answer that question?
A.100 years
B.10 years
C.Never
D.1 year
Which of the following is NOT a scientific observation?
A.The Sun is very hot.
B.Dr. Mastrapa is 1.83 meters tall.
C.Alpha Centauri is 4.4 light years away.
D.The mass of the Earth is 5.972 x 10^24 kg.
