What opportunities for service did trained nurses such as those recruited by this poster have during the war?

The opportunities are:

- to work as Medical professionals in a millitary base

- Part of Medic soldiers that provide first aid in the battle field.

- to work as nutritionists for the soldiers

- To work as a part of red cross

Trained nurses had the option to either join their country's millitary or join a neutral party to be involved in the war.

If they choose to serve their country, their skill set would be used to treat ill / wounded soldiers in the camp, ensuring that the soldiers have the energy necessary for the war, or learn to use a weapon and join as the medic that goes a long with the soldiers to the battle field.

If they choose a neutral party such as the red cross, they can provide medical assistance for all the soldiers that involved in the war. Those soldiers are banned to shoot the redcross since they are only there to provide medical help to both sides.

B. They could volunteer for the Red Cross or serve in the military Nurse Corps

Explanation:

a stronger central government  

its what they are