Gnpth wrote:
Geologists once thought that the molten rock known as lava was an underground remnant of Earth's earliest days, sporadically erupting through volcanoes, but they now know that it is continuously created by the heat of the radioactivity deep inside the planet.
(A) was an underground remnant of Earth's earliest days, sporadically erupting
(B) had been an underground remnant of Earth's earliest days and sporadically erupted
(C) was an underground remnant of Earth's earliest days, which sporadically erupted
(D) would be an underground remnant of Earth's earliest days that sporadically erupted
(E) was an underground remnant of Earth's earliest days, having sporadically erupted
I'm happy to respond.
Apparently, this is a
MGMAT question, and as usual, it's a good one.
One grammatical feature that appears in this sentence is the
sequence of tenses. The geologist "
thought" something in the past, so the verbs describing the content of what they thought should follow the rules of the sequence of tenses.
When the geologist were alive and doing this "thinking," they thought that in their own present time, the lava was a remnant. This is in the geologists' present time, so it should be in the same tense as we use for the geologists, the past tense. We need the past tense, "
was," not the past perfect "
had been," nor the hypothetical "
would be." We can eliminate choices (B) & (D).
Choices (A) & (C) & (E) are identical up to the comma, and then have
(A) ...
sporadically erupting = fine, the correct tense
(C) ...
which sporadically erupted = also the correct tense, but a bit wordier
(E) ...
having sporadically erupted = changes the tense from the prompt, so this changes the meaning
In (A) & (C), the "erupting" is also in the geologist present time, the same time the remnants existed. In the prompt, all three happen in the same general time period: (1) the geologist thinking, (2) lava was a remnant, and (3) the erupting. Both those choices keep those three events in the same time period. Choice (E) puts the erupting in an earlier time period from the others, and that's a change in meaning, so (E) is wrong.
Both (A) & (C) are grammatically & logically right, but (C) is a little wordier, so (A) is the best.
Does all this make sense?
Mike