Which of the following pairs of atomic numbers represent s-block elements?

The pair of atomic numbers 3 and 12 represent s-block elements.
s-block elements are the elements present in group 1 and 2 of the long form of periodic table. They are 14 in number, namely hydrogen(1), lithium(3), helium(2), beryllium(4),sodium(11), magnesium(12), potassium(19), calcium(20), rubidium(37), strontium(38), caesium(55) , barium(56), francium(87) and radium(88).
 Hence, the correct answer is 3;12.