In 1992 outlaw fishing boats began illegally harvesting lobsters from the territorial waters of the country of Belukia. Soon after, the annual tonnage of lobster legally harvested in Belukian waters began declining; in 1996, despite there being no reduction in the level of legal lobster fishing activity, the local catch was 9,000 tons below pre-1992 levels. It is therefore highly likely that the outlaw fishing boats harvested about 9,000 tons of lobster illegally that year.
A选项=NOT (96年非法龙虾捕捞特别多, 以至于该水域的可捕捞龙虾数量急剧减少)
NOT A选项=(96年非法龙虾捕捞特别多, 以至于该水域的可捕捞龙虾数量急剧减少)
If NOTA, then (1996年合法和非法的捕捞总量)<(1992年合法和非法的捕捞总量)
这与原题暗含假设相悖. 因此A选项是原题的假设.