How are interstellar bubbles made? A) by the collapse of a gas ...

[LCritchfi]

How are interstellar bubbles made?
 
  A) by the collapse of a gas cloud to form stars
  B) by the rapidly rotating magnetic fields of pulsars
  C) by the winds of massive stars and supernovae explosions
  D) by the ejection of planetary nebulae from low-mass stars
  E) by collisions between the Milky Way and satellite dwarf galaxies

Question 2

What is the evidence that suggests planetary systems are common in the universe?
 
  What will be an ideal response?

[jxjsniuniu]

Answer to Question 1

C

Answer to Question 2

We know that stars form surrounded by disks of gas and dust, that there is enough material in these systems to form many planets, and that, theoretically, planet growth should be common in these disks. Observationally, we have detected Jupiter- (and even Saturn-) mass planets around nearby stars using the Doppler technique, and the Kepler mission has shown (via transits) that a majority of stars have planets.

[LCritchfi]

Excellent

[nathang24]

Gracias!