Indefeasibility of title means: 

a. That the title of the registered proprietor cannot be defeated by another person who claims they have an interest in the land unless the other person has an unregistered equitable interest in the land. 

b. That the title of the registered proprietor can be defeated by another person who claims they have an interest in the land. 

c. That the title of the registered proprietor can be defeated by another person who claims they have an interest in the land if they have written evidence of that interest. 

d. That the title of the registered proprietor cannot be defeated by another person who claims they have an interest in the land.