Answer:
The best answer for this question is "d. can never censor student speech"
Step-by-step explanation:
The freedom of speech is internationally institutionalized as a human right under the article 19 of the Universal Declaration of Humans Rights and therefores if the government of a country voted in favor of the declaration of human rights they should guarantee freedom of speech in their territory, if a public school (have noted that public school are not private entities so they are reagulated by the government) censor in any way the speech of any student they are infringing this human right, so the best option is D, can never censor student speech.