Clear serial port receive buffer in C#

Just want to know how do we clear the receive buffer of my serial port in C#. Seems like the data in the receive buffer just keep accumulating. For example, the flow of incoming data is: [Data A], [Data B], [Data C]. The data I want is just [Data C]. I'm thinking of doing like, when I receive [Data A] and [Data B], I do a clear buffer. Only when [Data C] is received, I continue process. Is this the way to do it in C#?