Which other elements of the periodic table do halogens readily
react with to form halide salts?

Variables,control,conclusion and finally scientific theory

Ibelieve your answer is true 

A) the enthralling of formation for pure element in its standard state is always positivehope this : )

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.