Question

why do some scientists believe the universe is made up of both regular and dark matter?

the rotation of stars and solar systems around the milky way

it is because of the oscillating action of the universe.

the steady state of the universe requires both kinds of matter.

the wilkinson microwave anisotropy probe of cosmic radiation showed temperature variations for both types of matter.

Explanation:

To determine the answer, we analyze each option:

• Option 1: The rotation of stars and solar systems around the Milky Way is not a key reason for the belief in both regular and dark matter.
• Option 2: The "oscillating action of the universe" is not a recognized reason for positing both regular and dark matter.
• Option 3: The steady - state of the universe does not inherently require both regular and dark matter in the way this option suggests.
• Option 4: The Wilkinson Microwave Anisotropy Probe (WMAP) measured cosmic microwave background radiation. The temperature variations in this radiation provide evidence for the composition of the universe, including the presence of both regular and dark matter.

Answer:

D. The Wilkinson Microwave Anisotropy Probe of cosmic radiation showed temperature variations for both types of matter.