In order to find the actual length of the 4 inches side, we can use the following rule of three:
[tex]\begin{gathered} 9\text{ inches}\to36\text{ yards} \\ 4\text{ inches}\to x\text{ yards} \\ \\ \frac{9}{4}=\frac{36}{x} \\ \frac{1}{4}=\frac{4}{x} \\ x=4\cdot4 \\ x=16 \end{gathered}[/tex]So the actual length of this side is 16 yards, therefore the correct option is B.