The complex structure of the adhesive footpad of the gecko, having

Few Queries:
1)Could anyone please clarify verb-ing Modifier or phrase "with its...",modifying which noun?
Having hairlike structures : Modifying Geko? or Complex Structure?
2)In option E : I doubted about "its" doesn't hv clear antecedent.
Also option E if plugged into original sentence , "the complex structure....with its hairlike structures called fibrillar adhesives, helps....": Doesnt sound convincing.

Pls help me to figure out the gap. Thanks in advance.

1) "with it" is a modifier modifying the noun 'Geko'
This isn't a complex structure . Complex sentences are made
up of one independent clause (or main clause) and one or more dependent
clauses (or subordinate clauses). The dependent clause is introduced and linked
to the independent clause by a subordinating conjunction
2) 'It' refer backs to complex structure .A pronoun can refer back to an antecedent in the former clause. long distance relationships do work.
On GMAT , most of the answer choices don't sound convincing but we have to pick the best among them, A choice which communicates the proper intended meaning and which is grammatically correct.

Please correct me if my analysis is wrong.

A. having hairlike structures called fibrillar adhesives, help clarify why researchers have posited that it

Incorrect
if having is modifying the noun then it should not be preceded by comma. Since it is preceded by comma, having must modify the preceding action but it seems that having is giving information about the “adhesive foot pad”.

SV not in agreement: the complex structure (singular) help( plural).



B. having hairlike structures that are called fibrillar adhesives, helps clarify why researchers have posited that it

Same modifier error as in option A. SV error is rectified in this option.



C. with its hairlike structures that are called fibrillar adhesives, helps clarify why researchers have posited that they

“Its” correctly refers to the “adhesive foot pad”. Pronoun they( plural) refers to the “ complex structure” ( singular). Hence agreement error.

D. with its hairlike structures called fibrillar adhesives, help clarify why researchers positing that it
SV verb error. It should be helps instead of help
E. with its hairlike structures called fibrillar adhesives, helps clarify why researchers have posited that it
Correct choice.

Posted from my mobile device

The logical question here is to ask what has the hair like structures. We can eliminate the gecko because it is not the animal that has hair like parts. It is only the adhesive footpad. Whether it is a complex structure or a simple structure does not matter much to us as long as it is a sticky footpad. Therefore, in all sense, the pronoun 'it' should refer to the footpad rather than anything else.

We cannot surmise that researches posited researches as in C, if we were to take 'they' for researchers. However, they can be either the structures or the adhesives. However, unfortunately the plural is in an inessential modifier and if the modifier is ignored, then the pronoun 'they' has no sensible referent. Hence, we have to drop choice C.

Between B and D, both the words 'having' and 'with' can only modify the eligible singular noun footpad. However, B is avoidably wordy by adding the phrase 'that are called".

D is the choice.

although I got this correct but can someone explain use of "having" vs "with" along with some examples ?

In which case use of "having" could be right ?