Final answer:
The four pairs of fricatives are /v/ - /f/, /th/- /th/, /s/-/z/, /sh/ - /zh/ and they differ in voicing and /h/. (option A).
Step-by-step explanation:
The four pairs of sounds are /v/ - /f/, /th/- /th/, /s/-/z/, /sh/ - /zh/ and they differ in voicing. The term that correctly describes these pairs is A) Fricatives. Fricatives are consonant sounds produced by forcing air through a narrow channel made by placing two articulators close together. Voicing refers to whether the vocal cords vibrate during the production of the sound.
The sounds in each pair differ by voicing; one is voiced and one is unvoiced. For example, /v/ is voiced whereas /f/ is unvoiced.
Hence, the answer is option A.