Which of the following is an unaided communication strategy?

Facial expressions are an unaided communication strategy because they rely solely on the individual's own body language and emotional expressions to convey meaning. This form of communication does not involve any external tools or aids; instead, it utilizes the natural ability of individuals to express feelings, reactions, or responses through their facial movements.

In contrast, written language, digital photos, and symbols all involve external supports or tools to communicate. Written language requires the use of text; digital photos rely on visual imagery created with devices; and symbols typically consist of graphic representations that aid in communication. These methods provide additional forms of expression beyond what the body can naturally convey, thus categorizing them as aided communication strategies.