The Main Difference Between Regular Open-Market Operations and Quantitative Easing

The main difference between regular open-market operations and quantitative easing (QE) is:

A) whether the Fed is buying or selling financial assets
B) the type and term of the financial assets targeted.
C) whether the Fed is trying to increase or decrease interest rates
D) that open-market operations is conducted by the Fed, while quantitative easing is mandated by congress.