My Ans is A.

However the OA is C.
B, you can eliminate easily.My problem with C is that it changes the meaning of the original sentence.

[spoiler]A [underlined sentence] : In all, fifteen or more

C:at least fifteen[/spoiler]

Hence I do not agree with C....Please correct me if I am wrong !

[spoiler]Source : Veritas.

Solution: C

Explanation: The easiest answer choice to eliminate is (B) as the past perfect is clearly incorrect in this case: it suggests they were tied to insider trading before they were at the fund. Also (D) is incorrect as the semi-colon is incorrectly used in that case - it should be separating an independent clause. In (A), the past tense could be correct, but the structure at the end is not parallel and it is imprecise. The "and more likely" does not make it clear what is more likely and does not logically follow the structure before it. In (E), "the more are likely" is also incorrect as something needs to follow it because the structure before cannot be logically put after it. You cannot say: "four have pleaded guilty and more are likely have pleaded guilty" Only (C) gets the second part correct: the semi-colon is used to separate an independent clause and it uses the proper "to do so" after "more likely" to show that "four have pleaded guilty and more are likely (to plead guilty). Answer is (C).[/spoiler]

Hey, meaning comes after grammar.

I think you would agree that other options have glaring grammatical errors. In this case, except option C, none of the options is correct.

In A and B, "more likely" is kept hanging (not parallel to with X...).

In E, "more are likely" is not parallel to "four have pleaded guilty".

In D, post semicolon, we do not have an independent clause.

We are left with C alone here.

Please note that there are other errors too in wrong options, but you need only one error to eliminate the choices.

P.S. The meaning will come into play when you have two grammatically correct sentences.

Hope this helps!