What advance improved communications during world war i?

 The correct answer is :  In 1917 appeared in the armies of Britain and France, new telephone switching equipment that made communications much more effective. Also appeared telephone networks that resisted more the effect of shellfire. The radios were very large and unreliable, also used pigeons, heliographs, flags, flares but were very limited in their use.

necessary and proper clause. the congress shall have power to all laws which shall be necessary and proper for carrying into execution the foregoing powers, and all other powers vested by this constitution in the government of the united states, or in any department or officer thereof.

c. is the western hemisphere.