In the above reaction,the electrophile is substituted at the meta position only,due to:
$I$. Electron density is more at ortho $\&$ para positions
$II$. Electron density is relatively less at ortho $\&$ para positions
$III$. Electron density is less at meta position
$IV$. Electron density is relatively more at meta position
The correct answer is:

• A
  $I, III$ only
• B
  $II, IV$ only
• C
  $I$ only
• D
  $III$ only