Critical Reasoning

Early in the twentieth century, Lake Konfa became very polluted. Recently fish populations have recovered as release of industrial pollutants has declined and the lake's waters have become cleaner. Fears are now being voiced that the planned construction of an oil pipeline across the lake's bottom might revive pollution and cause the fish population to decline again. However, a technology for preventing leaks is being installed. Therefore, provided this technology is effective, those fears are groundless.
The argument depends on assuming which of the following?
A. Apart from development related to the pipeline, there will be no new industrial development around the lake that will create renewed pollution in its waters.
B. Other than the possibility of a leak, there is no realistic pollution threat posed to the lake by the pipeline's construction.
C. There is no reason to believe that the leak-preventing technology would be ineffective when installed in the pipeline in Lake Konfa.
D. Damage to the lake's fish populations would be the only harm that a leak of oil from the pipeline would cause.
E. The species of fish that are present in Lake Konfa now are the same as those that were in the lake before it was affected by pollution.

Confused b/w B and D . Experts please suggest