Which of the following is true of a closed Universe?

Which of the following is true of a closed Universe?
 
  A) It is infinite.
  B) It has a center.
  C) It has a negative curvature.
  D) It has a positive curvature.

Question 2

The__________is the period of time after the glow of the big bang faded into the infrared and before the birth of the first stars, during which the Universe expanded in darkness.
 
  A) space age
  B) dark age
  C) atomic age
  D) ice age

Question 3

If there were lots of baryons present during the early moments of the big bang, they would have:
 
  A) collided with deuterium to make helium.
  B) collided with lithium to make helium.
  C) collided with and destroyed deuterium.
  D) collided with each other to from deuterium.

Question 4

As the 21st century began, which of the following is a discovery made by astronomers?
 
  A) The Universe has a center.
  B) The expansion of the Universe is actually accelerating.
  C) The Universe has an edge.
  D) The expansion of the Universe has come to a halt.