Explanation:

- The circumference of the semicircle is given as 36 cm. Use the formula for the circumference of a semicircle: \( \text{Circumference} = \pi r + 2r \), where \( r \) is the radius.

- Plugging in values, \( 3r + 2r = 36 \) cm. Simplifying gives \( 5r = 36 \), so \( r = 7.2 \) cm.

- The radius of the semicircle is the same as the breadth of the rectangle, which is 7.2 cm.

- The area of the rectangle is given as 216 cm². Use the area formula \( \text{Area} = \text{length} \times \text{breadth} \).

- Plugging in the given values, \( 216 = \text{length} \times 7.2 \). Thus, \(\text{length} = 216 / 7.2 = 30\) cm.

Option 3 - 30 cm