The average temperature of the lobster-rich waters off the coast of Foerkland has been increasing for some years. In warmer water, lobsters grow faster. In particular, lobster larvae take less time to reach the size at which they are no longer vulnerable to predation by young cod, the chief threat to their survival. Consequently, the survival rate of lobster larvae must be going up, and the lobster population in Foerkland' s coastal waters is bound to increase. Which of the following, if true, most seriously weakens the argument? ["Cod are a cold-water species, and the increasing water temperatures have caused a northward shift in Foerkland's cod population.", 'There are indications that in recent years the fishing fleet operating off the coast of Foerkland has been taking cod at an unsustainably high rate.', 'The increase in water temperatures off Foerkland has not been as pronounced as the increase in average soil temperatures in Foerkland.', 'Because of their speeded-up growth, lobsters now get large enough to be legal catch before they reach reproductive maturity.']