Which of the following orders regarding relative stability of free radicals is correct?

• A
  $3^\circ < 2^\circ < 1^\circ$
• B
  $3^\circ > 2^\circ > 1^\circ$
• C
  $1^\circ < 2^\circ > 3^\circ$
• D
  $3^\circ > 2^\circ < 1^\circ$