"Natural higher" is a vague term. It is not uncommon to find questions that are not worded accurately in biochemistry. I have found such questions in major exams! Fatty acids may be short-chain (SCFA), medium-chain (MCFA), long-chain (LCFA) or very long chain (VLCFA). By "natural", I assume this is made by the human body. Common fatty acids contain even number carbon atoms (since they are made from the 2-carbon acetyl CoA), are cis-isomers. Some, like linoleic acid and linolenic acid (with double bonds beyond C9) cannot be synthesized by humans and must be obtained from the diet (they are thus essential fatty acids). Odd chain fatty acids (long chain) and very long chain fatty acids are broken down in pathways different than beta-oxidation of saturated fatty acids. Most fatty acids with multiple double bonds are not conjugated. However, conjugated fatty acids are found in nature (not made by humans) but are very rare. An example is rumenic acid.
