Question

what would most likely cause the future acceleration of the expansion of the universe?- radiation from the sun- the existence of background radiation- the continued existence of dark energy- light shifts identified by the doppler effect

Explanation:

• Solar radiation only affects our solar system, not universal expansion.
• Cosmic background radiation is leftover heat from the Big Bang, not a driver of accelerated expansion.
• Dark energy is a mysterious repulsive force that is currently causing the universe's expansion to accelerate; its continued existence would drive future acceleration.
• Doppler light shifts are an observation that confirmed cosmic expansion, not a cause.

Answer:

the continued existence of dark energy