Which of the following conditions resolves on its own within a few days and is benign?

Erythema Toxicum Neonatorum is a common and benign rash seen in newborns, typically presenting as small, red spots or macules that might be surrounded by a white or yellow pustule. It appears during the first few days of life and usually resolves spontaneously within one to two weeks without any treatment. This condition is a normal part of newborn skin development, and its self-limiting nature is an important characteristic that makes it benign.

In the context of understanding the other options: Cephalohematoma involves bleeding between the skull and the periosteum, which generally resolves on its own over time but can be associated with complications. Hemangiomas are vascular tumors in infants that may require monitoring and potential intervention if they do not resolve on their own after a few months to years. Mongolian Spots are benign, blue-gray birthmarks that may fade over time, but they do not have the characteristic acute presentation or resolution pattern seen with erythema toxicum neonatorum. Each of these conditions has unique attributes, but only erythema toxicum neonatorum is a transient condition that characteristically resolves swiftly and is considered benign.