Which of the following does not apply to sets?

Select one:

$$ a$.$ The stored elements can be of different data types.

O b$.$ All the elements must be unique: you cannot have two elements with the same

value.

a$.$The stored elements can be of different data types.

b$.$ All the elements must be unique: you cannot have two elements with the same

value.

c$.$ The elements are unordered.

d$.$ The elements$$are$$in$$pairs$.$