Hi GaneshMalkar,
Thank you for the post
You have correctly identified that in option A 'splitting' is the present participle form while in option B it is a gerund.
But I notice that you have stated that in choice A "splitting" is a verb. To ensure that you understand the concept well, I will ask a question:
The cat running behind the rat eventually caught it.
In the above sentence, do you think that "running" acts as verb or as a verb-ing modifier?
Likewise, look at the sentence below:
The cat was running behind the rat and eventually caught it.
Now in the above sentence, do you think "was running" is a verb?
What is the difference in how "running" has been used in the two sentences?
Now let's look at the sentence structure to find out more about the function of 'splitting', assuming that you are of the understanding that "splitting" is not a verb..
- "¢ New theories propose
o that catastrophic impacts of asteroids and comets may have caused
 reversals in the Earth's magnetic field,
 the onset of ice ages,
"¢ splitting apart continents 80 million years ago,
 and great volcanic eruptions.
So, this sentence consists of a list of elements that might have been stimulated by the catastrophic impacts of asteroids and comets.
In the list, the present participle 'splitting' seems to modify the preceding clause, since it is placed after a clause and preceded by a comma.
This modifier tells us how the catastrophic impacts may have caused the onset of ice ages. How? By splitting apart continents. This is illogical since the splitting apart of continents cannot contribute in the onset of ice ages.
So, to make this sentence logically correct, it makes sense to make this element parallel to the other three elements of the list, and hence, it is converted into a gerund noun in option B.
Notice what we did here.
1: We first understood the roles played by different entities in the sentence by understanding the sentence structure
2: Then we applied the logical check and found that the sentence is illogical the way it is written
3: Lastly, we brainstormed and thought what meaning would actually make sense given the context of the sentence and how best we can express that meaning.
So sentence structure and meaning are the keys
Hope this helps!
Deepak
