What gave the allies and advantage at the battle of coral sea
a. great britain had a much better navy thab japan.
b. hitler refused to send aid to the german troops.
c. the russian winter proved tii treacherous for german troops.
d. code breajers were able to warn of the planned japanese attack

The code breakers were able to warn of the planned Japanese attack and this gave the allies the advantage at the battle of coral sea. The correct option among all the options given in the question is option "d".The allies were able to predict the plans of Japanese attack and invasion beforehand and this helped the Allies to make their plans accordingly. The Japanese were very surprised at the response they got from the allied forces and the response from the allied forces also damaged vital aircraft carriers of the Japanese army as well. 

Executive should be the answer