GMATPrep run-on choice?

A SC question from GMATPrep:

With no natural predators and expanses of green suburban neighborhoods that allow no hunting, wildlife officials estimate the New Jersey deer population to have grown to exceed 175,000

A. With no natural predators and expanses of green suburban neighborhoods that allow no hunting, wildlife officials estimate the New Jersey deer population to have

B. With no natural predators and with expanses of green suburban neighbourhoods that do not allow hunting, wildlife officials' estimate of the deer population in New Jersey has

C. With no natural predators and with expanses of green suburban neighborhoods where there is no hunting, the deer population in New Jersey, wildlife officials estimate, has

D. Without natural predators and no hunting allowed in expanse of green suburban neighborhoods, New Jersey has a deer pupulation that wildlife officials estimate to have

E. Without natural predators and with expanses of green neighborhoods where there is no hunting, wildlife officials in New Jersey estimate a deer population that has

C is the answer. But does "wildlife officials estimate" cause run-on problem?

Thanks.

Somehow, I still feel this insertion is awkward. Although I have seen this type of insertion before, I do not remember seeing it in OG. Do you think an "as" is needed before the inserted sentence?

as作连词，在GMAT语法中表示比较，如果加入as的话结构就不对了。