What Is the Difference Between a Company's Intranet and the Internet

What is the difference between a company's intranet and the Internet?

A) Internet sites can be hacked into, but intranet sites are safe.
B) People's Internet use can be monitored, but intranet use is impossible to monitor.
C) People can access email using the Internet, but not using company intranets.
D) The Internet is publicly accessible, but company intranets are accessible only to employees.
E) None of the above is correct; the Internet and a company's intranet are exactly the same thing.