The element in the third group and third period in modern periodic table isA.CarbonB.AluminiumC.BoronD.Cobalt

The modern periodic table is arranged in increasing order of atomic numbers in horizontal rows called periods and vertical columns called groups.

1. The third period of the periodic table includes the elements from Sodium (Na) to Argon (Ar).

2. The third group of the periodic table (also known as Group 13) includes the elements Boron (B), Aluminium (Al), Gallium (Ga), Indium (In), Thallium (Tl), and Nihonium (Nh).

3. Therefore, the element that is in the third group and third period of the modern periodic table is Aluminium (Al).

So, the answer is B. Aluminium.