Free radical activity can be characterized by:

The correct characterization of free radical activity is oxidative stress. Free radicals are unstable molecules that have unpaired electrons, which makes them highly reactive. They can cause damage to cells, proteins, and DNA by stealing electrons from those structures in a process that leads to oxidative stress. This stress occurs when there is an imbalance between free radicals and the body's ability to counteract their harmful effects through antioxidants.

Oxidative stress is linked to various health issues, including aging and chronic diseases, which is why understanding its relationship with free radicals is essential in fields like cosmetology, where skin health is a primary concern.