OE


The sentence says that "no one submitted a construction project proposal if another expressed concerns." Each of the engineers could look over a proposal before submission, and thereby act as "an overseer to" the others. The only other option that gives that same meaning is "a reviewer for," since reviewers check for issues. "A go between for" and "a negotiator for" are an incorrect pair, since there is nothing in the sentence that suggests that the engineers negotiate with each other. A "hindrance to" is tempting but has a negative spin, and there is nothing in the sentence suggesting that the relationship is negative. Similarly, "an estimator for" is attractive because construction project proposals involve estimates, but the second part of the sentence says that the issue was only whether other engineers "expressed concerns" about project feasibility or cost estimates. It does not say that the engineers performed each others' cost estimates, so "an estimator" is going too far.