Dextromethorphan. This is a drug that is used for this purpose and is considered an anti-tussive.
A membrane lipid is a compound which belongs to a group of (structurally similar to fats and oils) which form the double-layered surface of all cells (lipid bilayer). The three major classes of membrane lipids are phospholipids, glycolipids, and cholesterol.
I believe it's the first one.
An increased rate of evaporation would allow the funnel to grow increasingly larger as the storm updraft takes in warm moist air at a more rapid rate. This would also increase the strength and speed of the tornado's winds. With that said, your best answer is D.