Answer:
C) They all have single covalent bonds.
Step-by-step explanation:
The given hydrocarbons Butane,Ethane,Methane,Propane belongs to alkane group.
In alkane group consists of hydrogen and carbon in which carbon_carbon bonds are single and carbon_hydrogen bond is also single.
The elements of this group makes bond by sharing of electrons that means they form single covalent bond.
Butane have 4 , Ethane has 2, Methane has 1, and Propane has 3 carbon atoms.
Since they have different number of carbon atoms so their structural formula also differs.