Septimus has a seven-sided coin. he turns it over from right to left in front of him, rotates it 3/7 turn clockwise, turns it over again in the same way, and then turns 1/7 anticlockwise. this is the same as a clockwise turn by which of the following?
A. 2/7
B. 3/7
C. 4/7
D. 5/7