In single laced solumn construction, the thickness of the flat lacing bars shall not be less than :

A

$$\frac{1}{15}$$ th of the width of the lacing bar

B

$$\frac{1}{30th}$$ th of the width of the lacing bar

C

$$\frac{1}{40}$$ th of the width of the lacing bar

D

$$\frac{1}{10}$$ th of the width of the lacing bar