a) polar heads on the outside and nonpolar fatty acids on the inside
Explanation:
The cell membrane is made up of phospholipids arranged in a bilayer, where hydrophilic polar (negatively-charged) heads of phospholipids interact with water molecules (i.e., aqueous surrounding media). Moreover, non-polar (uncharged) fatty acid tails are hydrophobic because they cannot be dissolved in water. Thus, the bilayer cell membrane is a structure where non-polar fatty acid chains are localized in the inner region (away from the water), while hydrophilic phosphate heads face outward, interacting with water on both sides of the cell membrane.
A lit candle needs to draw oxygen from the air in order to continue burning. If you limit the amount of air available, the candle's flame eventually goes out once it uses up all the oxygen. Lit candles in smaller jar stop burning first because the oxygen trapped in the jar are fewer than the ones in bigger jars.
