31. What does PCM stand for in digital-to-analog conversion?
a) Pulse Code Modulation
b) Phase Code Modulation
c) Packetized Code Modulation
d) Parallel Code Modulation

32. How does delta modulation represent changes in analog signals?
a) By comparing with previous values
b) By quantizing each sample
c) By encoding changes directly
d) By sampling at fixed intervals

33. Which keying technique has the lowest bandwidth efficiency?
a) Amplitude Shift Keying
b) Frequency Shift Keying
c) Phase Shift Keying
d) Differential Phase Shift Keying

34. What does multiplexing primarily aim to achieve?
a) Data compression
b) Bandwidth optimization
c) Error correction
d) Signal amplification

35. Which switching method offers a guaranteed data rate during a connection?
a) Circuit switching
b) Datagram switching
c) Virtual circuit switching
d) Packet switching