Consider the following$$ items:

a$.$ the album$"21"$ by Adele

b$.$ a Dutch$$ horticulturalist's new method for cultivating hybrid tulips

c$.$ Rolls$$ Royce's "Spirit of$$ Ecstasy" hood ornament design

d$.$ the sale of Tumi luggage at a$$ Macy's department store

Which of the items listed is an example of intellectual$$ property?