Take a look at the following letter written by Abraham Lincoln. What indicates that it is a primary source?

A letter written by Abraham Lincoln in 1854

The letter is dated.

It is a handwritten document.

The letter looks old.

Abraham Lincoln was the president in 1854.

If this question has multiple answers, it'd be that the letter is dated and it is a handwritten document. If it's multiple choice. I'd say, logically, it'd be a handwritten document because anyone can put a date on a paper but it's very difficult to recreate someone's handwriting. Also, considering it was in 1854, they used feather pens and ink.