How do scientists determine motion of objects in the universe?

A. heliocentric theory

B. big bang theory

C. geocentric theory

D. Doppler effect

Actually its D.Doppler effect

Explanation:

Because they never mentioned anything about the heliocentric theory and the geocentric theory and the big bang theory is about how they thought the universe was before the big bang happend so that leaves you with the doppler effect.

world bank is the correct answer.

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the correct answer is :

{b.}   ( american workers lose job opportunities )

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    -sprinkles