GMAT Critical Reasoning (CR) | Re: storm waters introduced Pacific carp

Since 2004, when storm waters introduced Pacific carp to Hoffman Lake, the lake’s population of smallmouth bass has decreased by nearly one third. In the same time period, the lake’s population of sand trout has decreased by approximately 40%. Still, Hoffman Lake is home to more sand trout than to any other type of fish.

Which of the following must be true on the basis of the statements above?
A.If plans to remove Pacific carp from Lake Hoffman are successful, the population of smallmouth