Answer:
A is a period and B is a group
Explanation:
The given figure shows a portion of a blank periodic table. We have to identify the segments labeled A and B.
A = period
B = group
Period is defined as the horizontal row of the periodic table. It relates the number of shells of an atom of the given element. All element of a period have same number of atomic orbitals. Group is defined as the vertical row of the periodic table. It relates the number of valance electrons of an element.
Hence, the correct option is (b) "A is a period and B is a group".
