Correct option is : (A) \(sp ^ 2\)
\(SO_3\) is a combination of two elements one Sulphur and three Oxygen atoms. To understand the hybridization of sulphur trioxide we have to understand the bonding between sulphur and oxygen. If we draw and look at the Lewis structure sulphur will be the central atom and will have three double bonds with oxygen. In this, there is one sigma and one pi bond formed. This gives us the \(sp^2\) hybridization type.
