5.A. Given nine balls labeled with numbers $2,3, \cdots, 10$, two balls are randomly drawn, and their labels are noted. The probability that the larger label is divisible by the smaller label is ( ).
(A) $\frac{1}{4}$
(B) $\frac{2}{9}$
(C) $\frac{5}{18}$
(D) $\frac{7}{36}$
5. A. B.

Let the binary array $(a, b)$ represent the labels of the two balls drawn, where $a$ and $b$ are the smaller and larger labels, respectively. Then, the pairs $(a, b)$ that satisfy the condition are as follows:
$$
\begin{array}{l}
(2,4),(2,6),(2,8),(2,10), \\
(3,6),(3,9),(4,8),(5,10) .
\end{array}
$$

The total number of ways to draw the balls is $\frac{9 \times 8}{2}=36$, so the required probability is $\frac{8}{36}=\frac{2}{9}$.