Which of the following is true about ear medications?

Ear medications can indeed contain multiple active ingredients, which allows for more comprehensive treatment of various conditions affecting the ear. This is particularly important in real-world medical practice, as patients may present with multiple symptoms or issues that necessitate a combination of therapeutic agents. For instance, an ear drop formulation might include an antibiotic to address an infection and a corticosteroid to reduce inflammation simultaneously.

The other options do not accurately reflect the nature of ear medications. They may come in multiple forms, not limited solely to liquid; it's possible for them to treat more than one condition at a time; and while some ear medications are available only by prescription, many can also be purchased over-the-counter. Hence, option B accurately captures a defining characteristic of ear medications.