The correct answer is option 3, seven sigma bonds.

In order to determine the total number of sigma bonds in C2H6 (ethane), we need to first understand the structure of ethane. Ethane consists of two carbon atoms bonded to each other by a single sigma bond, with each carbon atom also bonded to three hydrogen atoms.

Each carbon atom forms four sigma bonds, one with the other carbon atom and three with hydrogen atoms. Therefore, in total, there are eight sigma bonds in ethane. However, we need to consider that each sigma bond is shared between two atoms.

Since there are two carbon atoms, each carbon atom shares one sigma bond with the other carbon atom and three sigma bonds with hydrogen atoms. This means that there are seven unique sigma bonds in ethane.

Therefore, option 3, seven, is the correct answer.