4 Blackbeard and his crew got chose to other ships by

Решение:

Текст гласит: "They often learnt a ship's nationality and then raised that country's flag in order to appear friendly. This way Blackbeard's ship could get close to the other ship." Это описывает использование флага другой страны для обмана.

Ответ: D showing the same flag as the other ship.