Answer:
The employees' actions are legal because they are acting together to influence their working conditions.
Explanation:
The following strikes are legal under Section 7 of the National Labor Relations Act (NLRA):
Economic strikes, in which employees attempt to pressure the employer to concede to their demands for improvements in wages, benefits or work rules;
Unfair labor practice strikes, in protest of an employer's committing an unfair labor practice; and
Sympathy strikes, which occur when employees choose not to cross a primary picket line out of sympathy for the primary striking employees.