Answer: A (overwhelmed)
Explanation: The last sentence says, “This fact was somehow mixed and confused with his opinion of his own situation that it seemed almost a proper reason for tears.” This shows that the guy was so sad because his situation was making him overwhelmed and want to cry.
For example you can say:
Dear Friend(or make up a name)
Today I went to the debate competition finals and it was amazing! We went against this school named (school name) and the competition was intense.
Or something like that, just giving you an idea. Make sure to add descriptive words and make sure to apply if you won or you lost.
Answer: It means you have to plan it out, as in understand what and how you're going to write the letter.
Hope this helps!