Question 986 Deck Safety

The correct answer is S. The symbol number 51 refers to the International Code of Signals (ICS), which is a standardized system of signals used for communication between ships and shore stations. In the ICS, the symbol 'S' is used to represent the letter 'S', which is a standard distress signal. The other answer choices (A, B, C, D) do not correspond to any recognized signal in the ICS, and therefore are incorrect.