Propane cylinders used in Ontario must be manufactured and approved according to the requirements established by?

The correct answer is Transport Canada, as propane cylinders in Ontario must meet the safety and transport regulations established by this federal agency. Transport Canada sets the standards for the design, construction, and certification of portable cylinders used for the transportation of dangerous goods, including propane.

When cylinders are manufactured, they must comply with the appropriate standards to ensure safety during handling and use. Transport Canada's regulations provide guidelines that must be followed for the testing and approval of these containers. This ensures that the cylinders are safe for transporting propane, which is a flammable gas, and helps to prevent hazards related to leaks, ruptures, or accidents during transport.

Other entities mentioned have different roles; for instance, the Canadian Standards Association (CSA) develops standards but does not have the regulatory authority that Transport Canada does for transportation safety. Similarly, the Technical Standards and Safety Authority (TSSA) focuses on the safe operation of gas appliances and equipment rather than the manufacturing standards of the cylinders themselves. The Canadian Gas Association (CGA) is involved in advocacy and technical standards related to natural gas and propane but does not govern cylinder manufacturing regulations.