What characteristic of the skin can change due to factors like humidity and temperature?

The correct answer is resistance. The resistance of the skin can vary based on external factors such as humidity and temperature. When the humidity is high, moisture on the skin's surface decreases its resistance, allowing electrical currents to pass through more easily. Conversely, when the skin is dry due to low humidity or cold temperatures, its resistance increases, making it more difficult for electrical currents to flow.

Understanding skin resistance is crucial in electrical safety practices, as it helps in assessing the risk of electric shock. If the skin's resistance is lower, a smaller voltage can lead to a dangerous current flowing through the body. This characteristic emphasizes the importance of environmental conditions in electrical work settings. While conductivity, sensitivity, and flexibility are also relevant attributes of the skin, resistance specifically relates to how electrical currents interact with the skin under varying environmental conditions.