Here's why:
* Sign languages are distinct: Each country or region has its own sign language, much like spoken languages. There's American Sign Language (ASL), British Sign Language (BSL), French Sign Language (LSF), and many more.
* No global standard: There's no universal sign language understood by everyone around the world.
* Different types of communication: Sign language isn't just a visual representation of spoken language; it has its own grammar, syntax, and structure.
Therefore, you can't rank sign language as a single entity among spoken languages.
However, here's what we can say:
* Many sign languages are widely used: Individual sign languages, like ASL or BSL, have large user bases within their respective countries and communities.
* Growing recognition and importance: Sign language is becoming increasingly recognized and respected as a legitimate and vibrant language, with more and more countries incorporating it into their educational systems and public services.
Ultimately, sign languages are essential for deaf and hard-of-hearing communities around the world. While their individual rankings might not be clear-cut, their significance and impact on communication are undeniable.