Let $A = \{1, 2, 3, 4, 6\}$. Let $R$ be the relation on $A$ defined by $R = \{(a, b) : a, b \in A, b \text{ is exactly divisible by } a\}$. Find the range of $R$.

(A) The relation $R$ is defined as $R = \{(a, b) : a, b \in A, b \text{ is exactly divisible by } a\}$.
We check for each $a \in A$,which $b \in A$ satisfies the condition:
For $a = 1$: $b \in \{1, 2, 3, 4, 6\}$ (since $1$ divides all these numbers).
For $a = 2$: $b \in \{2, 4, 6\}$.
For $a = 3$: $b \in \{3, 6\}$.
For $a = 4$: $b \in \{4\}$.
For $a = 6$: $b \in \{6\}$.
The set of all second elements (the range) is the set of all $b$ values that appear in the ordered pairs of $R$.
Range $= \{1, 2, 3, 4, 6\}$.