Which form of suspension is applied to the skin to reduce pain and stiffness?

Liniment is a form of topical suspension specifically designed to be applied to the skin, often to alleviate pain and stiffness in muscles and joints. It typically contains active ingredients such as analgesics or anti-inflammatory agents, which can penetrate the skin to provide relief from discomfort. The consistency of liniment allows it to be spread easily over the affected area, ensuring effective delivery of the beneficial components to the skin and underlying tissues.

In contrast, lotion generally has a lighter consistency and is often more moisturizing than therapeutic, making it less suitable for deep muscle pain relief. Gels, while they can also provide some topical relief, are usually intended for a cooling sensation and may not be as effective for deeply penetrating pain relief as liniments. Aerosols can deliver medication in a spray form but may not have the same targeted therapeutic effects as a liniment when it comes to pain and stiffness. Therefore, liniment is uniquely suited for its primary purpose, making it the correct choice in this scenario.