Time-To-Live is a key component of the IP datagram header format. Time to Live is an eight bit integer initialized by the original sender and decremented by each router that processes the datagram. What happens when the value of the datagram integer reaches a value of zero? O The datagram forms a loop and is resent by the original sender The datagram is discarded The datagram is sent to the next router, then returned to sender An error message is sent back to the source a and c above b and d above