What is the position of elements $La (Z=57)$ and $Ce (Z=58)$ respectively in the long form of the periodic table?

• A
  $La = \text{Group-}3, \text{Period-}6; Ce = \text{Group-}3, \text{Period-}6$
• B
  $La = \text{Group-}4, \text{Period-}7; Ce = \text{Group-}5, \text{Period-}7$
• C
  $La = \text{Group-}3, \text{Period-}7; Ce = \text{Group-}3, \text{Period-}6$
• D
  $La = \text{Group-}3, \text{Period-}6; Ce = \text{Group-}3, \text{Period-}7$