What tones would you use if told to strike the common chord of C in four-part, close harmony, using the root for the highest tone?
A C chord is composed of the tones C, E, and G. The root is C. In a four-part chord, the bass is typically also the root. So, we have a C in the bass and a C in the soprano. A closed chord indicates that the alto should be the closest harmonizing note (beneath the soprano) and the tenor should be the next closest harmonizing note coming down.
Because this is a four part harmony, the bass doesn't have to be the next lows harmonizing note. The interval between the tenor and the bass can be as large as we wish. In this case it is a tenth.