Which excerpt from Tinker v. Des Moines shows how precedent helps support an argument?

A. "Under our Constitution, free speech is not a right that is given only
to be so circumscribed that it exists in principle, but not in fact.
Freedom of expression would not truly exist if the right could be
exercised only in an area that a benevolent government has
provided as a safe haven for crackpots."

B. 'I, for one, am not fully persuaded that school pupils are wise
enough, even with this Court's expert help from Washington, to run
the 23,390 public school systems (n4] in our 50 States.

c. "As we shall discuss, the wearing of armbands in the
circumstances of this case was entirely divorced from actually or
potentially disruptive conduct by those participating in it. It was
closely akin to pure speech' which, we have repeatedly held, is
entitled to comprehensive protection under the First Amendment.
Cf. Cox v. Louisiana, 379 U. S. 536,555 (1965). Adderley v. Florida,
385 U. S. 39 (1966)."
cm

D. "While the absence of obscene remarks or boisterous and loud
disorder perhaps justifies the Court's statement that the few
armband students did not actually disrupt the classwork, I think
the record overwhelmingly shows that the armbands did exactly
what the elected school officials and principals foresaw they
would."