Answer B
In asynchronous transmission, for each character, we need to send data, parity, start and stop bits.
Size of one character = 7+1+1+1 =10 bits
Line transmits 3200 bits in.one second.
No of characters transmitted in one second = 3200/10 =320
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NOTE
In synchronous transmission, we need to send ONLY data and parity in each character
Size of a character =7+1=8
Number of characters sent in one Second =3200/8=400