"Its fossil record" como resposta de um exercício

Eu tive uma dúvida num exercício diário que eu faço, dê uma olhada:

Part of the following sentence is underlined; beneath the sentence are five ways of phrasing the underlined material. Select the option that produces the best sentence. If you think the original phrasing produces a better sentence than any of the alternatives, select choice A.

Its fossil record virtually unchanged over 100 million years, the Ginkgo tree is one of the oldest living species of tree.

(A) Its fossil record
(B) Its fossil record was
(C) Its fossil record, which is
(D) Its fossil record exists
(E) Its fossil record, because

Fonte: http://sat.collegeboard.com/practice/sa ... of-the-day

Resposta: A
Explicação: Choice (A) is correct. It avoids the errors of the other options by using the phrase “Its fossil record” to describe what has remained “virtually unchanged over 100 million years.”

Mesmo assim eu não entendi, poderiam me esclarecer por favor?