Which of the following statements is true about nonverbal signals?

Nonverbal signals encompass a range of communication methods that do not rely on spoken or written language. Both the tone of voice and the various forms of physical expression—like facial expressions, gestures, postures, and eye contact—are fundamental components of how we convey feelings and attitudes without using words. This makes the first statement true, as it encompasses the full spectrum of nonverbal communication.

Additionally, the phrase "body language" is commonly used to refer to these nonverbal cues, further supporting the accuracy of the assertion that they are often categorized as such. Recognizing body language is critical for understanding an individual's true feelings or reactions, as it often conveys more than spoken words.

Thus, affirming the correctness of both the first and the third statements leads to the conclusion that the fourth option, which combines both true assertions, is the most comprehensive and accurate choice.