I believe the correct answer is C) He carried a hammer that returned to him when he threw it.
It is the only option that keeps all the essential elements of the sentence, without changing its meaning, but cuts out enough words to make it shorter and less redundant.
If we go by exclusion:
A) is not correct because in this case we don't want to keep the sentence as it is.
B) We are missing part of the sentence, the one about the hammer coming back.
D) Wonderful is an adjective that is not necessary to keep the meaning of the sentence and thus can be removed.
This is why C) is the correct answer.
