5. Until now, trying to stop this illegal trade has been more or less futile. The oceans are vast. Navies and coastguard patrols are small. Even finding those who are up to no good has been hard. That, though, is changing through the use of "bid data." It is now feasible to synthesise information from sources such as radio transponders and satellite observations, in order to track every ocean-going _______ that is, or might be, a fishing boat.(A) missile (B) vaseline (C) vase (D) vessel