Answer
a. No.
b. 3
c. 3
Work Step by Step
a. These are not equivalent for the same reason that a shoe is not the same thing as a box containing a shoe.
b. The number of elements in a set (called the cardinality of a set) is given by the number of unique elements in a set.
c. Using the shoebox analogy, this set is a box containing (1) a shoe, (2) another box containing a shoe, and (3) another box containing a shoe and a box with a shoe in it.
