The correct answer is: Log
A log is a length of a felled tree trunk that has been trimmed of branches and bark. It is a raw material that can be used to make a variety of products, such as lumber, paper, and fuel.
A batten is a narrow strip of wood or metal used for fastening or strengthening something. It is typically used in carpentry and joinery.
A plank is a long, flat piece of wood or other material, typically used for flooring or building construction.
A baulk is a large, heavy piece of timber, typically used in construction or shipbuilding.
In conclusion, the trunk of a tree left after cutting all the branches is known as a log.