$3$ is related to $2$ following a certain logic. Following the same logic, $9$ is related to $6$. Which of the following numbers is related to $12$ using the same logic?

Let's find the ratio or operational logic between the given pairs of numbers:
1. First pair: $3$ is related to $2$.
The operational relationship can be written as:

$$3\times \frac{2}{3}=2$$

2. Second pair: $9$ is related to $6$.
Let's check if the same scaling factor applies:

$$9\times \frac{2}{3}=3\times 2=6$$

(The logic is consistent)

Now, let the missing number related to $12$ be $x$. Following the same constant ratio logic:

$$x\times \frac{2}{3}=12$$

Solving for $x$:

$$x=12\times \frac{3}{2}$$

$$x=6\times 3=18$$

Therefore, the number related to $12$ is $18$.