The question is incomplete as the group of choices are not available, however the answer is given on the generalized knowledge.
Answer:
The correct answer would be : A distress flag.
Explanation:
VDS stands for the visual distress signal use by the people who is in some sort of distress or lost with their boat mainly. VDS involve mainly pyrotechnic and non pyrotechnic visual distress signals to attracts attention towards them in distress.
A non pyrotechnic VDS is type of VDS that does not involve any type of exothermic reaction or flare gun to bring attention. These Non pyrotechnic VDS can also be different on the basis of the time of the use. The approved day time non pyrotechnic distress signal is The distress flag. The size of the flag must be at least 3 × 3 feet with a black square and ball on an orange background.
D is the answer. The first 3 are not good communication.