What common characteristic is generally shared by the elements at the center of a period?
a. they are nonmetals.
b. they have the lowest atomic mass.
c. they are the least reactive elements.
d. they have the most orbitals.

I think the correct answer would be C. The common characteristic that is shareed by the elements found at the center of a period would be that they are the least reactive species. Having lower value of electronegativity, there is less ionization of the atoms which would also contribute to less reactivity.

Aconductor easily transfer heat

Ci hope  it  you