Consider the equation $Z = \frac{pV}{RT}$. Which of the following statements is correct?

• A
  When $Z = 1$,real gases are easily compressible.
• B
  When $Z > 1$,real gases are more compressible than ideal gases.
• C
  When $Z > 1$,real gases are difficult to compress.
• D
  When $Z = 1$,real gases are difficult to compress.