  We explore multi-terminal quantum transport through a benzene molecule
threaded by an Aharonov-Bohm flux $\phi$. A simple tight-binding model is used
to describe the system and all the calculations are done based on the Green's
function formalism. With a brief description of two-terminal quantum transport,
we present a detailed study of three-terminal transport properties through the
benzene molecule to reveal the actual mechanism of electron transport. Here we
numerically compute the multi-terminal conductances, reflection probabilities
and current-voltage characteristics in the aspects of molecular coupling
strength and magnetic flux $\phi$. Most significantly we observe that, the
molecular system where the benzene molecule is attached to three terminals can
be operated as a transistor, and we call it a molecular transistor. This aspect
can be utilized in designing nano-electronic circuits and our investigation may
provide a basic framework to study electron transport in any complicated
multi-terminal quantum system.
