Which of the following persons is not exempt from the licensing provisions of the Professional Engineers Act?
A) An employee of a communications company under the jurisdiction of the Public Utilities Commission when prepáring plans for communication lines.
B) A private citizen who designs his own one-story wood frame residence, which complies with Title 24.
C) A licensed contractor when designing an electrical or mechanical system that he or she is legally contracted to install.
D) A licensed contractor designing complete commercial buildings that she or he has contracted to construct.