Which sentence from the passage includes a subordinating conjunction?

“Contemporary architects often turn to nature for design inspiration and problem solving.” (paragraph 3)

“The design offers a space-saving feature as well—circular stairs and ramps take up less space than traditional horizontal structures.” (paragraph 7)

“Most recently, these architects have been trying to create environmentally friendly structures that serve the needs of the population, while still aesthetically pleasing to the eye.” (paragraph 3)

“There are many forms in nature that can inspire biomimicry.” (paragraph 4)