Which of the Following Did Harry Nyquist in 1928 First

Which of the following did Harry Nyquist in 1928 first demonstrate mathematically?

A) An analog signal can be reconstructed from periodic samples.
B) Pulses can be time-division multiplexed over a single communication channel.
C) The sample rate must be at least twice the highest frequency of the intelligence or information signal to be sampled.
D) Analog signals are quantized to the closest binary value provided in the digitizing system.