How does the author unfold ideas in paragraphs 13 - 15?
[13] Furthermore, Gu said, "With the immediate carbon emission reduction benefit from replacing fossil-based non-renewable concrete and steel with renewable mass timber products, the urgent climate change crisis can be mitigated now to help save our future."
[14] Regardless of wood product size, trees will store carbon. That's the case for nanocellulose. It is made by breaking wood (or plant) fibers down to nano-scale rods and filaments.
[15] Nanocellulose can be produced sustainably, has low environmental impact, and is biodegradable. Adding nanocellulose to existing products, such as concrete or plastic, can reduce carbon emissions because nanocellulose can make materials and products perform better, so less of the material is needed to do the same job.
A.by stating a fact, providing a detailed explanation, and then giving a successful example
B.by declaring an issue, describing a process, and then the pros and cons of that process
C.by presenting a goal, defining a scientific material, and describing how it reacts with other materials
D.by introducing a problem, providing possible solutions, and then choosing the best one