text: You are playing the game Starcraft-II. Your task is to control two marines, namely marine 1 and marine 2, to defeat two marines of the enemy, namely marine 3 and marine 4. 
  
  Marine 1 and marine 2 are in the shoot range of marine 3 and marine 4. Also,  marine 3 and marine 4 are in the shoot range of marine 1 and marine 2.
  
  Our marine 1 and marine 2, can choose the following actions:
  A. attack marine 3
  B. attack marine 4
  C. move forward
  D. move backward
  
  Which action should marine 1 choose? which action should marine 2 choose?