What are the possible combinations of multiple bonds and rings if a compound's index of hydrogen deficiency equals 3?

Question

Quizplus · Accepted Answer

The index of hydrogen deficiency (IHD) is calculated by subtracting the number of hydrogen atoms a compound would have if it were saturated (meaning all carbons are single bonded to each other and have the maximum number of hydrogens possible) from the actual number of hydrogen atoms in the molecule. The result is then divided by two. Therefore, an IHD of 3 indicates the presence of three pi bonds (double or triple bonds) or three rings or a combination thereof. Option C provides all possible combinations of three rings with pi bonds (double or triple), including two rings with a double bond, one ring with two double bonds, and one ring with a triple bond, as well as one double bond and one triple bond in the same molecule.

What Are the Possible Combinations of Multiple Bonds and Rings