How the atomic radius (the size) of elements changes as we go down?

Radius of atoms increase as you go down, can decrease from left to right in certain periods

The further down from the group (top to bottom) the atomic radius increases, while the energy level (left to right) decreases

Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.

There is no reason to think the results are biased or not conducted properly but you should not assume the results are correct just because they were done in a laboratory so the answer would be c. it is likely to be reliable because the results support the conclusion presented.