An air traffic control unit gives you an instruction. What must you do as pilot-in-command?

1. 1Comply with it but do not acknowledge it
2. 2Ignore it if you are flying VFR
3. 3Acknowledge it but decide later if you comply
4. 4Comply with the instruction and acknowledge it to the ATC unit

Source: Canadian Aviation Regulations (SOR/96-433), CAR 602.31(1) Compliance with Air Traffic Control Instructions and Clearances