Which of the Following Statements Describes Picketing

Which of the following statements describes picketing?

A) Strikers gathered at a place of business can prevent people from doing business with employer.
B) Picketing is permissible only when contract negotiations are taking place and there is no lawful strike mandate.
C) Picketing must be peaceful and merely communicate information.
D) Courts or labour relations boards cannot restrict picketing even when regulations are violated.
E) Picketing is permissible where workers cease working because of a dispute over the interpretation of a term of their collective agreement.