The NLRB can rule that actions of a third party have had a negative impact on employee free choice in union elections and declare the vote invalid.

​Carbon isotope dating is useful in studying the history of life because ____.

A) ​the ratio of ¹⁴C to ¹²C in living organisms changed at key geological events
B) ​12C decays at a set rate based on a set time scale
C) ​14C is incorporated into fossil remains only
D) ​carbon is only incorporated into living organisms
E) carbon is lost uniformly once an organism dies