All observable objects outside our galaxy, when viewed from Earth, have their spectra shifted to slightly longer wavelengths. Astronomers have concluded that this is evidence that all objects in the universe are-

A. hotter than our Sun.
B. moving away from each other.
C. older than our solar system.
D. absorbing radiation from stars.

Option B.

Moving away from each other.

Explanation:

The spectra emitted by the objects in the solar system refer to the electromagnetic waves that are emitted from the object.

When viewed from the earth the shifting of the spectra to longer wavelengths suggest that the objects are not in the same position as they used to be. This is because the time the waves take to reach the earth have changed, thus suggesting also a change in their position.

the answer is b. apsidal precession