Which of the following statements about market efficiency is true?

A market must be weak-form efficient if it is semi-strong form efficient.

A market can be semi-strong form efficient but not weak-form efficient.

A market can be semi-strong form and strong-form efficient but not weak-form efficient.

A market can be semi-strong form, weak-form or strong-form efficient but not all simultaneously.

A market must be weak-form efficient if share prices are random.