Molecular Clouds Can Be Observed

Multiple Choice

Molecular clouds can be observed

A) using infrared telescopes to detect ionized gas in the clouds.
B) using x-ray telescope to observe the x-ray radiation from the molecules in the cloud.
C) using radio telescopes to observe the CO emission from the clouds.
D) by looking for blue wispy regions near star clusters.
E) by looking for the 21-cm radiation from hydrogen.