Use the perimeter formula. Perimeter = 2 × (Length + Breadth).<br><br>
&bull; 2 × (L + B) = \( \frac{9}{10} \)<br>
&bull; L + B = \( \frac{9}{10} \div 2 = \frac{9}{20} \) m<br>
&bull; L = \( \frac{2}{5} = \frac{8}{20} \) m (convert to same denominator)<br>
&bull; B = \( \frac{9}{20} - \frac{8}{20} = \frac{1}{20} \) m<br><br>
Final Answer: D: \( \frac{1}{20} \) m