Geologists once thought that the molten rock

[rachelhong2012]

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.

was an underground remnant of Earth's earliest days, sporadically erupting

had been an underground remnant of Earth's earliest days and sporadically erupted

was an underground remnant of Earth's earliest days, which sporadically erupted

would be an underground remnant of Earth's earliest days that sporadically erupted

was an underground remnant of Earth's earliest days, having sporadically erupted


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Even though this problem already exists on the forum, the issue that the person had with this problem is not the same as mine. I am not sure I understand the explanation for the last choice becaue I don't know what tense is "having erupted", it is present perfect or past perfect? Thanks!


MGMAT explanation: (E) In this choice, "having sporadically erupted" incorrectly places this modifier in the past tense, implying that lava no longer erupts through volcanoes.

[tim]

To talk about something having happened means it’s over and occurred in the past. The precise term attached to the tense is irrelevant..

[Jov]

As I understood from Ron' post that comma + verb + ing modifier should be used only in two cases:

If ING action is simultaneous with, and subordinate to the main action
Or
Direct and immediate consequence

Right answer doesn't satisfy any of these. Please explain.

Thanks a lot in advance.

[RonPurewal]

As I understood from Ron' post that comma + verb + ing modifier should be used only in two cases:

If ING action is simultaneous with, and subordinate to the main action
Or
Direct and immediate consequence

Right answer doesn't satisfy any of these. Please explain.

Thanks a lot in advance.

This question has been removed from the CAT database, for precisely this reason.