In case of timber structures, the form factor for solid circular cross-section is taken as A. 1.18 B. 1.414 C. 1.67 D. 1.81

The correct answer is A. 1.18.

The form factor is a dimensionless number that is used to calculate the bending strength of a beam. It is defined as the ratio of the second moment of area of the cross-section to the product of the width and depth of the cross-section.

The form factor for a solid circular cross-section is 1.18. This means that the bending strength of a solid circular beam is 1.18 times the bending strength of a beam with the same width and depth but a rectangular cross-section.

The other options are incorrect because they are not the form factor for a solid circular cross-section.