The specific conversion formula of bit rate and baud rate is: R=Blog2N.

According to the topic, now R=2B means N=4, QPSK (quadrature phase shift keying or quadrature phase shift keying): quadrature phase shift modulation uses four different carrier phases to represent the input digital information, and specifies four carrier phases, which are 45, 135, 225, 3 15 respectively. QPSK can transmit 2 information bits per modulation.

In this option, only QPSK has 4 symbol types.