The widely accepted big bang theory holds that the
universe began in an explosive instant ten to twenty
billion years ago and has been expanding ever since.

(A)          that the universe began in an explosive instant
ten to twenty billion years ago and has been
expanding

(B)          that the universe had begun in an explosive
instant ten to twenty billion years ago and had
been expanding

(C)          that the beginning of the universe was an
explosive instant ten to twenty billion years ago
that has expanded

(D)          the beginning of the universe to have been an
explosive instant ten to twenty billion years ago
that is expanding

(E)          the universe to have begun in an explosive
instant ten to twenty billion years ago and has
been expanding

The sentence describes the central tenet of a
theory about how the universe began. The focus
of the second clause should be consistently on
the subject the universe, and all verbs in the clause
beginning with that must describe what the
universe did at the initial explosive moment.

A    Correct. Both verbs in the second clause
correctly take universe as their subject.

B    Had begun is the wrong tense because it

describes action that occurred farther in the
past than some other, specified past action.

C    The relative clause that has expanded

describes instant, which makes no sense.

D The beginning of the universe to have been ... is
unnecessarily indirect and wordy; illogically
suggests that beginning is expanding, not the
universe.

E    The verb phrases to have begun and has been
expanding both reference the same subject of
the clause, universe, and therefore need to be
parallel.

The correct answer is A.

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i'm confused with the explanation of E: why A is parallel but E is not ?