What type of injury is classified as a concussion?

A concussion is classified as a type of brain injury that typically results from blunt force trauma to the head. This impact can lead to a disruption in normal brain function, which may occur with or without loss of consciousness. The mechanism behind a concussion involves rapid movement of the brain within the skull, which can cause chemical changes and potential damage to brain cells.

The other options describe different types of medical conditions or injuries that do not align with the definition of a concussion. Severe injuries accompanied by hemorrhaging usually indicate a more significant trauma with possible bleeding and structural damage to the brain. A blockage of a blood vessel in the brain refers to conditions like strokes, which are not classified as concussions. A progressive decline in cognitive abilities is indicative of neurodegenerative disorders like dementia but does not relate to the acute impact nature of a concussion. Thus, the correct classification of a concussion directly connects to blunt force trauma, making this choice the most accurate.