Calculate the area of a rectangle of sides 6m and 3m respectively.

$$
\text{Area} = 6 \text{m} \times 3 \text{m}
$$

$$
\text{Area} = 18 \text{m}^2
$$
*   The options are not visible for this question, but the calculated area is $\boxed{\text{18 m}^2}$.