THE CORRECT ANSWER IS B. THE ORIGINAL SENTENCE CONTAINS THE UNIDIO...
11. The correct answer is B.
The original sentence contains the unidiomatic "formed out of"
instead of the idiomatic "formed from". Moreover, the relative
pronoun "which" must refer to the immediately preceding noun,
which in this case is the illogical "Earth." The correct referent is
"moon". We need a choice that makes this clear.
The only choice that remedies all the issues without creating new
ones is B.