The protocol data unit for the transport layer in the internet stack is
The answer is segment or datgram.
Please refer this:https://googleweblight.com/?lite_url=https://en.m.wikipedia.org/wiki/Protocol_data_unit&ei=uq_L7G_X&lc=en-IN&s=1&m=933&host=www.google.co.in&ts=1465980048&sig=APY536x3an3pqM6p-WScTPDbjnaQLwaJbg
@shivanisrivarshini, it doesn't matter what you think, it is standard:D
ans is (a)
The Layer 2 (Data Link Layer) PDU is the frame
. The Layer 3 (Network Layer) PDU is the datagram.
The Layer 4 (Transport Layer) PDU is the segment