Britain is now rabies free.
Conclusion
Britain's strict quarantine of imported domesticated animals cannot succeed in indefinitely preventing widespread outbreaks of rabies.
Intermediate Conclusion
This policy cannot control rabies spread by wild bats.
Evidence (since)
Bats fly into Britain from continental Europe. Wild bats cannot be quarantined.
Evaluate
In the vernacular of Method questions, we usually think about whether the argument ever did one of these things: - analogy - bad implications - (counter)example to general - calls out dubious assumption - raises overlooked consideration - makes a definition / distinction - suggests alternate explanation - rules out other options
This felt like the author was rebutting a plan by raising an overlooked consideration. The plan might solve part of the problem (rabies from domesticated animals) but not other parts of the problem (rabies from wild bats who fly in).
Goal
Let's find an answer whose language descriptively matches the argument.