Which of the following is classified as an analgesic or painkiller?

Aspirin is classified as an analgesic or painkiller because it is a nonsteroidal anti-inflammatory drug (NSAID) that works by inhibiting the production of certain chemicals in the body that cause pain and inflammation. It is commonly used to relieve mild to moderate pain, such as headaches, muscle aches, and menstrual cramps. Additionally, aspirin has anti-inflammatory properties and can also reduce fever, which further supports its classification as a pain-relieving medication.

In contrast, insulin is a hormone that regulates blood sugar levels and is primarily used in the management of diabetes. Vitamin D is a nutrient essential for bone health and immune function, rather than pain relief. Penicillin is an antibiotic used to treat bacterial infections but does not have pain-relieving properties. Thus, among the choices provided, aspirin is the only one that specifically fits the definition of an analgesic or painkiller.