$1.$ Which of the following SQL statements isn$$t valid?

a$.$ SELECT address $||$ city $||$ state $||$ zip "Address" FROM customers

WHERE lastname $$ 'SMITH';

b$.$ SELECT $*$ FROM publisher ORDER BY contact;

c$.$ SELECT address, city, state, zip FROM customers

WHERE lastname $$ "SMITH";

d$.$ All the above statements are valid and return the expected results.