Choose the best answer in question to complete the blanks in the text below.

Seafaring has, through history, always been one of the most dangerous occupations. Even today that is still true. Many countries had unilateral regulations on safety (18) sea trade is of international nature, the rules and regulations (19) be set up internatioally, (20) by individual countries, to make them better overall. To improve this subject, in 1948 the basis was laid for IMO.

(Ship Knowledge – A Modern Encyclopedia – K. Van Dokkum 2003)