C# How to store string values in a list outputted from a loop

Question

Q: How can I capture the data within my string list. After it's been looped? Therefore, I can use the list variable elsewhere in my method.

Goal: The output to the console needs to contain the value of what it's holding (i.e. the alphabet letters). The function only runs one time. In my progress...my desired/expect outcome almost-occurs when I loop my list a.k.a my string value within a foreach loop. However, I only want the output data one time...so a for loop is preferable (because it only runs once.)

I believed the simplest way to solve my dilemma is to add another for loop to iterate over the existing list. Then print the index + 1, and the value at that index to find the solution. But I am having issues.

Expected output (only runs once in a loop)

ABC
DEF
GHI
JKL
MNO

Example Code:

            var FriendsList = new List<string>();
            foreach (var friends in Obj.users)
            {
                FriendsList.Add(friend.user);

                foreach (var i in FriendsList)
                {
                    Trace.WriteLine(i);
                }

            }

Undesirable output example:

001
001
002
001
002
003
001
002
003
004
001
002
003
004
005

I don't believe this to be a good solution

//Using Linq to itterate over an array
var Arr = new string[4] {"one", "Two", "Three", "Four"};
Trace.WriteLine(Arr.Select((s, i) => $"Item no: {i + 1}, Value: {s}"));

It's wasteful.

I appreciate the help! Please provide examples.