Which best describes the present-day universe?
1. opaque, expanding very slowly, stars produce heavy elements
2. transparent, expanding at an accelerated rate, stars produce heavy elements
3. opaque, expanding at an accelerated rate, stars produce only hydrogen and helium
4. transparent, expanding very slowly, stars produce only hydrogen and helium

2. transparent, expanding at an accelerated rate, stars produce heavy elements

Explanation:

The Universe became transparent to the light left over from the Big Bang when it was roughly 380,000 years old, and remained transparent to long-wavelength light thereafter.

The accelerating expansion of the universe is being observed because the velocity at which a distant galaxy is receding from the observer is continuously increasing with time.

A star burns/fuses hydrogen to helium. This is the process that occurs during most of a star's lifetime. After the hydrogen in the star's core is exhausted, the star can burn helium to form progressively heavier elements.

B. Transparent, expanding at an accelerated rate, stars produce heavy elements

Explanation:

he kicked it 10 feet straight up into the air? i think this works.

need to see circuit to get time constant