Answer
$A \cap D = \left\{4\right\}$
Work Step by Step
Recall:
The intersection of sets $A$ and $D$, denoted by $A \cap D$, contains all the elements that are common to both sets.
Note that the element that is common to the sets $A$ and $D$ is $4$.
Thus,
$$A \cap D = \left\{4\right\}$$
