Correct answer is (a) Raised Heel Roof Truss
The best explanation: This is one of the most efficient types of timber roof trusses, mostly because it brings a very good room for insulation, but at the same time it also provides you with a very good system for structural support. It might require some additional materials in order to make it bring the best results, not to mention that the costs can be a little higher when compared to other truss types, but it does help you lower the energy bill value, so keep that in mind.