Final answer:
The NLRA (National Labor Relations Act) provides protection to the employee from termination for refusing to cross the picket line during a lawful picket.
Step-by-step explanation:
The law that provides protection to the employee from termination for refusing to cross the picket line during a lawful picket is the NLRA (National Labor Relations Act). The NLRA guarantees the right of workers to join unions and collectively negotiate with their employers. It prohibits discrimination against union members and prohibits employers from firing workers after a strike or other actions used to intimidate workers and union members.