Can you explain why some transport-layer packets may be lost in the Internet?

I’m working on a Computer Science multi-part question and need an explanation to help me learn.I just need the answers for these questions. its a graded hw assignment. 1. Can you explain why some transport-layer packets may be lost in the Internet?2. What is the minimum size of a UDP user datagram? What is the maximum size of a UDP user datagram?3. Which of the following is a random-access protocol? a. CSMA/CD; b. Polling; c. TDMA