Polylactic acid is the correct answer
They diffuse through small pores at the bottom of the leaf called stomata.
Plants can open and close their stomata, they open them to get water and carbon dioxide in but then close them to ensure the water doesn't 'leak' back out. This is important for plants growing in drier conditions like the cactus.
Gas molecules have more freedom in motion—and gases can be thought of as more “disordered”—than molecules of a solid, which are rigidly held in place. When it comes to phases, the entropy increases as you go from a solid to liquid to gas (the gaseous state having the greatest entropy and the solid state having the least).
So, as a sample of solid iodine sublimes to form gaseous iodine, the entropy of the sample increases.