Pho, an employee of Quality Food Service LLC and a member of Restaurant Workers Union, has a grievance with the company. In this context, it is not an unfair labor practice for the company to

a $.$

refuse to recognize the employee $$ s otherwise protected rights.

b $.$

all of the choices are unfair labor practices.

c $.$

solicit other employees $$ ?views on the union and make the views public.

d $.$

bar the union $$ s participation in a grievance proceeding to support Pho.