The correct option is E The data collected in the current geological survey provide a strong warning for engineers in consideration for the new dam project, but the greatest importance
First of all, "Data" can be used as either plural or singular. But the usage data as plural is more common.
Second. Because of "they", we should consider data plural noun.
The data being collected in the current geological survey are providing a strong warning for engineers as they consider the new dam project, but their greatest importance might lie in how they influence the upcoming decision by those same engineers on whether to retrofit 75 bridges in the survey zone.
A. The data being collected in the current geological survey are providing a strong warning for engineers as they consider the new dam project, but their greatest importance
>>> Wrong. "they" and "their" are not clear.
B. The data being collected in the current geological survey provide a strong warning for engineers as they consider the new dam project, but its greatest importance
>>> Wrong.
C. The data collected in the current geological survey is providing a strong warning for engineers as they consider the new dam project, but their greatest importance
>>> Wrong.
D. The data collected in the current geological survey provides a strong warning for engineers in consideration of the new dam project, but its greatest importance
>>> Wrong.
E. The data collected in the current geological survey provide a strong warning for engineers in consideration for the new dam project, butthe greatest importance
>>> Correct.