question: What is Gaussian frequency shift keying (GFSK)? option 1: A set of interconnected basic service sets (BSSs) option 2: Change of association between STAs in a wireless network option 3: A modulation scheme using Gaussian frequency shift keying (GFSK) option 4: A randomly assigned value used to protect group addressed medium access control (MAC) protocol data units (MPDUs) option 5: A location within an earth-centric frame of reference 