The baud rate is the rate at which information is transferred in a communication channel.
Serial ports use two-level (binary) signaling, so the data rate in bits per second is equal to the symbol rate in bauds.
Ref: https://en.wikipedia.org/wiki/Serial_port#Speed.
$\text{“9600 baud"}$ means that the serial port is capable of transferring a maximum of $\text{“9600 bits per second".}$
So, transmission rate here $=9600\text{ bps}$.
An eight bit data (which is a char) requires $1$ start bit, $2$ stop bits and $1$ parity bit $=12\text{ bits}$.
So, number of characters transmitted per second $=\dfrac{9600}{12}=800$.
Correct Answer: $B$