In the given diagram,what are the regions $P, Q,$ and $R$?
$P \quad\quad Q \quad \quad R$

• A
  Inner Medulla $\quad$ Outer Medulla $\quad$ Cortex
• B
  Cortex $\quad$ Outer Medulla $\quad$ Inner Medulla
• C
  Medulla $\quad$ Outer Cortex $\quad$ Inner Cortex
• D
  Inner Cortex $\quad$ Outer Cortex $\quad$ Medulla