The Building Act is the correct answer because it is the legislation that specifically covers work being carried out on a building site. This act sets out regulations and requirements for construction, alteration, and maintenance of buildings to ensure safety and compliance with building codes. It addresses various aspects of construction, including permits, inspections, structural integrity, fire safety, and accessibility. The other acts mentioned in the question, such as the Transport Act, Historic Buildings Act, and Animal Protection Act, may have their own regulations and requirements but do not specifically pertain to work on a building site.