In a system using the Security Extensions, how does the Secure Monitor execute a switch...

Encrypts Secure register contents, sets the NS bit in SCTLR and branches directly to Normal world code

Saves Secure register contents, sets all registers to zero, sets the NS bit in SCTLR and branches directly to Normal world code

Saves Secure register contents, loads Non-secure ones from memory, sets the NS bit in SCTLR and performs an exception return

Sets the NS bit in SCTLR and performs an exception return - all registers are banked in hardware and switched automatically