Right option is (a) Raised Heel Roof Truss
For explanation I would say: This is one of the most efficient types of timber roof trusses, mostly because it brings 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.