Triple

Target entity: established the linguistic legitimacy of American Sign Language
Context triple: [William C. Stokoe, legacy, established the linguistic legitimacy of American Sign Language]

• A. “The Sign Language in Deaf-Mute Instruction”
  “The Sign Language in Deaf-Mute Instruction” is a seminal 19th-century work by educator Edward Miner Gallaudet advocating for the use of sign language in the education of deaf students.
• B. American Sign Language chosen
  American Sign Language is a natural visual-gestural language used primarily by Deaf communities in the United States and parts of Canada, with its own distinct grammar and vocabulary separate from spoken English.
• C. The Status of Linguistics as a Science
  The Status of Linguistics as a Science is a seminal 1929 essay by Edward Sapir that argues for linguistics as a rigorous, autonomous scientific discipline and explores its methods and scope.
• D. Nordic sign languages
  Nordic sign languages are a group of related sign languages used across the Nordic countries, sharing historical roots and linguistic features while remaining distinct from one another.
• E. Language: An Introduction to the Study of Speech
  "Language: An Introduction to the Study of Speech" is a foundational 1921 work in linguistics that systematically explores the nature, structure, and function of human language.
• F. None of above.
• G. Unsure - the case is ambiguous/there is not enough information to decide.