Which sentence from the passage includes a subordinating conjunction?
[] “There are many forms in nature that can inspire biomimicry.” (paragraph 4)
[] “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)
[] “The design offers a space-saving feature as well—circular stairs and ramps take up less space than traditional horizontal structures.” (paragraph 7)
[] “Contemporary architects often turn to nature for design inspiration and problem solving.” (paragraph 3)