Let's deal with the first two option A and B which are very similar.A. regarding the note, including
its maturity date, interest rate, and whether its credit rating is very secure or highly speculative,
which depends on the seller's financial status
B. regarding the note, including
its maturity date, interest rate, and credit rating,
which may range from very secure to highly speculative depending on the seller's financial status
First what jumps out to me is the use of the pronouns its and which.
The most logical referent for the "its" clearly is the "note" (or the bound but anyway both these words describe the same thing), we may argue that there is ambiguity, afterall information (which is a uncountable noun and therefore singular noun) could be that "its". But considering the meaning we clearly see that we are describing the information about the note (its maturity date, interests ...). Not the information's maturity date which clearly would be a non sense. Those kinds of ambiguity can remain in those cases, where the referent clearly is logical. We may consider that this is an ambiguity error but lets be conservative and keep it until we find (or we don't) a better option.
Furthermore, the use of which in A and B clearly tends in favor of B. Indeed the which in A doesn't seem to have a clear referent. It is supposed to refer to the risk's range of the note, but we are lacking such a clear noun in A. B in the contrary is way more clear. Therefore, even if we are conservative we keep B over A.
Now let's look at the other answer choices
C. regarding the note,
which includes the maturity date, interest rate, and its credit rating, which may range between very secure and highly speculative, depending on the seller's financial status
Here the which seems to refer to the note. So if we try to understand the conveyed meaning here, what can we infer ? The note would already include the informations concerning its maturity date,rates ... therefore what would be the point of the sentence ? Why would an investor even bother to request information if the note already includes it ?
Even if we, let say consider that the which can jump to refer to the word "information" as "regarding the note" could be considered a prepositionnal phrase that would allow such jump (I'm not even sure about that), it would be more or less the same issue : :requesting information which includes" would not mean anything. In my opinion we have proven with a meaning based approach that we can discard.
D. in regards to the note, including the maturity date and interest rate, and also its credit rating, which ranges from the very secure to the highly speculative, depending on the financial status of the seller
First the "and also" is close to a redundant issue, even though GMAT doesn't always consider that as an issue by itself.
I'm not a native speaker so I'm not 100% sure of the difference between "in regards to" and "regarding", I think the most idiomatic formulation is "regarding" but I can't dimiss D for that reason.
So on what basis could I choose D over B or not ? In my opinion the 'depending on the financial status of the seller' part as it stands creates ambiguity, it is an -ing modifier and it may well modify the 'are advised to request' (while is supposed to modify the ' ranges from ... if we want to convey a correct meaning) part of the sentence. We may understand 'The investors are requested to ... depending on their status', a nonsensical meaning.
E. Here we won't develop that much, the 'them' clearly has not logical referent, E out.
Finally I have chosen B. Even if the ambiguity of the 'its' remains I think the points I have mentionned concerning D tend to favor B over D.
I would be glad if one of the experts could enlight me concerning wether or not the reasons I've presented to choose D are correct or not, also about the idiomatic usage of in regards to\regarding.
It is one of the first time I post an answer so I hope it will help the others and it will be accurate.