In a series of cases, including Griswold v. Connecticut (1965), Roe v. Wade (1973), Eisenstadt v. Baird (1974), and Casey v. Planned Parenthood (1992), the Supreme Court recognized a sphere of private conduct that should be protected from unwarranted governmental intrusion. Although Griswold based the right of privacy on several provisions of the Bill of Rights, what is the current constitutional basis for the Court's decisions in these areas?

A - Right to be free from unwarranted searches under the Fourth Amendment.

B - Freedom of expression under the First Amendment.

C - Right to a fair hearing under the Due Process Clause.

D - Right to personal liberty under the Due Process Clause.