With no explanation, label text_A→text_B with either "DON'T KNOW", "NO" or "YES".
text_A: However, the principle of locality appeals powerfully to physical intuition, and Einstein, Podolsky and Rosen were unwilling to abandon it. Einstein derided the quantum mechanical predictions as "spooky action at a distance". The conclusion they drew was that quantum mechanics is a complete theory, but is not easily understood.
text_B: Is quantum mechanics a theory?
YES.