Meteor showers are made of
the icy debris of comets.
Sometimes they are visible
from earth.

These sentences have been
combined using an appositive
phrase. Which sentence below
punctuates the appositive
phrase correctly?

A. Meteor showers sometimes visible from
earth, are made of the icy debris of comets.

B. Meteor showers, sometimes visible from
earth, are made of the icy debris of comets.

C. Meteor showers, sometimes visible from
earth are made of the icy debris of comets.