Saturated fatty acid means that all the carbon-carbon bonds are single. So, carbons have the maximum number of hydrogen possible.
Unsaturated fatty acid means that at least one carbon-carbon bond is not single but double. So, the number of hydrogen bonded to carbon atoms is less than the maximum possible.
That the two fatty acids have the same chain length means that they have the same number of carbons. So, the saturated fatty acid will have more hydrogens than the unsaturated fatty acid has.
Answer: option C. hydrogen atoms.
