The primary barrier to protect the body against disease is:AHand washingBUnbroken skinCProtective glovesDShort fingernails

The primary barrier to protect the body against disease is B: Unbroken skin.

Here's why:

1. Unbroken skin: The skin is the largest organ of the body and serves as the first line of defense against infections and diseases. It acts as a physical barrier that prevents harmful microorganisms from entering the body.

2. Hand washing: While it is an important practice to prevent the spread of diseases, it is not the primary barrier. It is a preventive measure that we must take to ensure that our primary barrier (skin) remains unbroken and effective.

3. Protective gloves: These are not a primary barrier but rather a secondary protective measure, especially used in healthcare settings. They protect our primary barrier (skin) from coming into direct contact with harmful substances or infectious materials.

4. Short fingernails: Keeping fingernails short can help maintain cleanliness and reduce the risk of spreading germs, but it is not the primary barrier against diseases. It is a part of personal hygiene practices that support the effectiveness of our primary barrier (skin).