What is the correct way to complete the sentence below? Today black spots or sha...

Questão de Inglês da banca EN aplicada no concurso ESCOLA NAVAL (2009). Confira a resolução completa abaixo:

What is the correct way to complete the sentence below? Today black spots or shadow zones around Somalia only benefit pirates. ______________(1) well-lit watchtowers, in the form of maritime security outposts, can help change that.