The correct answer is: A. 270-10 Meters from outermost signal.
Detonators are placed on the absolute block section during thick and foggy weather to prevent collisions between trains. They are placed 270-10 meters from the outermost signal, which is the signal that indicates the end of the block section. This ensures that there is enough space between trains for them to stop safely if they cannot see each other.
Option B is incorrect because it places the detonators too close to the first stop signal. This would not give trains enough space to stop safely if they cannot see each other.
Option C is incorrect because it places the detonators too far from the outermost signal. This would not ensure that there is enough space between trains for them to stop safely if they cannot see each other.
Option D is incorrect because it states that there is no need to place detonators during thick and foggy weather. This is not true, as detonators are necessary to prevent collisions between trains.