Atomic radius of Ga (135 pm) is less than that of Al (143 pm) because

• A

  of the small variation in the inner core of the electronic configuration

• B

  the presence of additional 10d electrons which offers only poor screening effect for the outer electrons from the increased nuclear charge in gallium

• C

  Both (a) and (b) are true

• D

  Neither (a) nor (b) is true