Which of the following soft wood species used for structural lumber has the highest fiber bending and modulus of elasticity?

The choice of Douglas fir and Southern yellow pine as the species with the highest fiber bending strength and modulus of elasticity is grounded in their superior engineering properties. Both of these species are extensively used in construction due to their strength and stiffness, making them ideal for structural applications.

Douglas fir is known for its exceptional strength-to-weight ratio and is often utilized in beams and framing where high loads are expected. Its bending strength and modulus of elasticity are among the highest of softwoods, contributing to its widespread acceptability in the industry.

Southern yellow pine is another strong contender, often characterized by its density and tensile strength. It exhibits high rigidity and is typically used in lumber for heavy structural applications such as flooring and joists. The combination of these two species allows for optimal performance in construction contexts.

In contrast, the other options present combinations of species that generally do not have the same level of structural strength. For instance, white pine and cedar, known more for their lightweight and resistance to decay, do not match the performance metrics of Douglas fir and Southern yellow pine in terms of bending strength. Spruce and hemlock also have useful structural properties but fall short of the overall strength characteristics that Douglas fir and Southern yellow pine offer. Lastly, ponderosa pine and larch