Which of the following organic molecules have only single bonds? a) structural isomers b) geometric isomers c) saturated hydrocarbons d) unsaturated hydrocarbons

The answer is molecules can be saturated and it has no rings and only single bonds, or they may be unsaturated and can contain the rings or multiple bonds. Unsaturation is the element of rings and multiple bonds.  We should remember that saturated hydrocarbons have two times the number of carbons (N) plus two hydrogen atoms in them (2N +2).

not: both offer magnification to the atomic level.