Quadrature amplitude modulation (QAM) is a combination of ___________.
a. pulse amplitude modualation (PAM) and phase modulation (PM)
b. pulse amplitude modulation (PAM) and frequency modulation (FM)
c. amplitude shift keying (ASK) and frequency shift keying (FSK)
d. amplitude shift keying (ASK) and Phase shift keying (PSK)
Answer: D