Why did the era of nuclei end when the universe was about 380,000 years old?

What is the most appropriate method of gaining weight (muscle mass)

Why do we perceive objects as retaining their brightness under different lighting levels?

What's wrong with this ecological pyramid? (multiple choice)1. secondary consumers should be at the bottom of the pyramid2. the sun has an arrow leading to decomposers 3. primary consumers should come after the sun4. energy retained should increase from the bottom to the top5. the sun should be at the bottom of the pyramid