In response to a letter he had received from a little girl wondering if her friends were right about Santa Clause's existence, Francis P. Church wrote:" VIRGINIA, your little friends are wrong. They have been affected by the skepticism of a skeptical age. They do not believe except [what] they see. They think that nothing can be which is not comprehensible by their little minds. All minds, Virginia, whether they be men's or children's, are little. In this great universe of ours man is a mere insect, an ant, in his intellect, as compared with the boundless world about him, as measured by the intelligence capable of grasping the whole of truth and knowledge.
Which of these best describes this type of published response?

feature article
essay
editorial
autobiographical sketch