To launch high power rockets, one must secure authorization from which of the following?

To launch high power rockets legally in Canada, it is essential to secure authorization from Transport Canada and any relevant authorities that may have jurisdiction over the launch site. Transport Canada is responsible for regulating airspace and ensuring that all aerospace activities comply with safety and aviation regulations. This includes obtaining the necessary permits for launching rockets, especially those that reach high altitudes.

The requirement for authorization also extends to local authorities as they may have specific regulations governing land use, safety, and environmental considerations. Coordination with landowners is also critical, particularly if the launch site is on private property or if the rocket might land on someone's land during descent.

Thus, the combination of Transport Canada and any relevant local authorities ensures that all legal and safety protocols are adhered to, making this the correct answer.