GMAT Sentence Correction (SC) | Re: In metalwork one advantage of adhesive-bonding over

I think the point is:

The comparison of contact. Whether contact is continuous orat regularly spaced points. The meaning of the sentence is trying to point out contact done continuously is better than done regularly spaced.

For choices A, B, which sounds pretty reasonable at first glance, you reject them for not havingat

Only D makes the meaning complete.

The sentencegoes:
contact , blah blah blah, iseffected continuously over a broad surfaceinstead of a series
of regularly spaced points