Answer:
correct answer is a. A searchlight from the towing vessel in the direction of the tow
Step-by-step explanation:
correct answer is searchlight from the towing vessel in the direction of the tow because in the fog time we can not see light due to low visibility
so when we hear the vessel we will search that submerged body and always searching in the direction of we hear sound of vessel
so green or red light can not visible
and triangle shape also not visible all the time
so correct option is A