Set intersection theory $W = \{a,b,c\}, Z = \{W,\emptyset\}$

What is $Z\cap W$?

I'm not sure how to work this out as my thoughts would be
$$Z = \{W,\emptyset\}  = \{\{a,b,c\},\emptyset\}$$
Which means $Z \cap W = \{a,b,c,\{a,b,c\},\emptyset\}$

Or should it just be
$$Z = \{W,\emptyset\} = \{a,b,c,\emptyset\}$$
Which means $Z \cap W = \{a,b,c,\emptyset\}$

Or should it just be 
$$Z = \{W,\emptyset\}$$
Which means $Z\cap W = \{W,\emptyset,a,b,c\}$

Any thoughts would be appreciated!
The elements of $W$ are: $a,b$ and $c$

The elements of $Z$ are: $W$ and $\emptyset$

Can you see any element both in $W$ and $Z$? If yes, those elements are the answer. If there is no such element, then the answer is $\emptyset$.
Intersection = available in both the sets. So,

Z intersection W = W $ \rightarrow $ {a,b,c}