I would say (b) because this answer is the most focused. It's also a topic which would easily fit in a five paragraph essay, while the others would most likely require extensive research and would only fit in an at least ten page paper.
Dear Amy today was such an interesting day I saved in missing child when I was going to pick up some groceries I saw a little boy yelling for his mom I asked him are you OK he said no I need my mom and little little boy started crying so then I went to the police I am search for his mom
Answer: Dear Old cell phone,
I Absolutely love you. I loved texting on you. From making calls to scrolling Instagram was fun with you.
But I gave you a virus and now you suck. You can’t do anything not even turn on.
It’s too bad because we could have had so many more fun times
And now it has to be over. I wish we could stay longer but your virus makes you a pain I’ll just have to give you in. I’m sorry if this is painful but you have to go I can’t live without a cellphone social media is my life, Good bye...
Sincerely, ayannaelu